Buying blue helmets: The role of foreign aid in the construction of UN peacekeeping missions

Abstract

While the evolving nature and proliferation of UN peacekeeping operations in the post-Cold War period is well documented, we know less about how personnel are recruited for these missions. Furthermore, recent developments have rendered existing supply-side explanations for troop contributions less convincing. The increasing demand for personnel, along with stagnant UN reimbursement rates and the rising costs of participation that began during the 1990s, mean that it is less attractive than ever for developing countries to offer their own troops to what have become increasingly ambitious operations. Yet, we see a large pool of developing countries continuing to do so. To address this puzzle, we argue that UN member states with strong preferences for establishing peacekeeping missions have begun using foreign aid as an inducement to help potential contributors overcome the collective action problem inherent in multilateral peacekeeping operations. We uncover strong empirical evidence that these ‘pivotal states’ strategically allocate foreign aid to persuade contributing states to boost their contributions, and also to ensure that these missions continue to be staffed and maintained as costs rise, particularly during the post-1999 period. We also find that states are responsive to these financial inducements: foreign aid increases both the likelihood of contributing personnel and the size of a state’s contribution. Theoretically, this article advances the scholarly understanding of international organizations and cooperation by illuminating an informal, extra-organizational strategy by which IOs can facilitate cooperation.

Keywords

collective action foreign policy international organizations UN peacekeeping United Nations

Introduction

One of the most recent UN peacekeeping missions, the United Nations Mission in South Sudan (UNMISS) was organized to bring stability to the newly independent but war-torn country. As of March 2018, the mission consisted of 12,432 troops, provided voluntarily by UN member states. Of these, 359 – just 2.9% – came from OECD¹ member states. The remainder were drawn from a range of low- and middle-income countries, most of whom had little at stake in the conflict.

This pattern holds for other post-Cold War UN peacekeeping missions as well. As missions have increased dramatically in number, scope, and ambition since the 1990s, the division of labor between industrialized and developing countries has become more pronounced (see Figure 1). But while this discrepancy has

Figure 1.

UN peacekeeping troop contributions

been well documented by peacekeeping scholars, we know little about the process through which these missions are assembled and maintained.²

Although personnel recruitment nominally falls under the purview of the UN Department of Peacekeeping Operations, the methods used by the UN to recruit and assemble peacekeeping forces have been poorly understood until recently. According to the UN, once the mission is authorized by the Security Council, ‘the Secretary-General chooses a Force Commander and asks Member States to contribute troops, civilian police, or other personnel’ (Bellamy, Williams & Griffin, 2004: 50). Participation is voluntary and governments are reimbursed for their personnel deployment costs, but considering the magnitude of these costs, and the lack of punishment for non-participation, it seems unlikely that there is nothing more to the UN peacekeeping recruitment process than a request from the Secretary-General and a reimbursement.

Much of the extant peacekeeping motivations literature has assumed that states are driven by various private benefits, particularly the profits from troop cost reimbursements paid to participating governments. Recent research (e.g. Coleman & Nyblade, 2018; Passmore, Shannon & Hart, 2018) casts doubt on this assumption, showing that the escalating costs to contributors and the high demand for peacekeeping personnel render profit-based explanations problematic. Despite this, we see many states participating in UN operations with gusto. If profit-based explanations are no longer convincing, what accounts for such high levels of UNPKO participation? We offer an answer to this question.

Drawing on public goods and burden-sharing arguments, we build upon recent findings and argue that the escalating costs of peacekeeping and the demand for manpower have given contributing states leverage. They use this leverage to demand foreign aid concessions from UN member states with strong preferences for assembling peacekeeping missions, in exchange for promises to contribute to the mission. We argue that these aid transactions between major powers and contributing states play a key role in generating and maintaining peacekeeping forces. Using a sample of developing countries from 1971 to 2015, we present three new findings. First, we find that certain UN member states – those with interests in establishing a particular mission – target both low-level and major contributors with foreign aid in an effort to persuade them to increase and maintain their contributions. Second, contributors that suffer casualties in UN missions are found to receive increased aid from pivotal states as compensation to prevent them from defecting from missions to which they have committed. Finally, we show that aid from pivotal states is a strong predictor of the size of recipient states’ combat personnel contribution. Moreover, these effects are only present in the post-1989 period – when demand for manpower became most acute – lending further support to our argument.

Table I.

Top budget and personnel contributors, 1990–2015

Percentage of UNPKO budget paid		Total personnel
United States	28.4	Pakistan	153,888
Japan	10.8	Bangladesh	149,278
France	7.2	India	118,234
Germany	7.1	Nigeria	67,786
United Kingdom	6.7	Nepal	65,593
China	6.6	Ghana	57,761
Italy	4.4	Jordan	56,234
Russia	3.1	Ethiopia	53,943
Canada	2.9	France	40,383
Spain	2.9	Egypt	39,106

In addition to our original empirical findings, this article also makes two theoretical contributions. First, we challenge a common view within the foreign aid literature that aid allocation is primarily driven by the narrow security interests of donor states. We show that major powers have the power and resources to persuade smaller states to participate in the pursuit of these interests through the distribution of foreign aid. This should raise questions about the potential for foreign aid (or other types of side payments) to facilitate large-scale collective action on a wide range of issues, from multilateral military intervention to compliance with environmental agreements.

Additionally, we demonstrate how powerful UN member states use extra-organizational leverage to overcome institutional inefficiencies to both assemble and maintain UN peacekeeping missions, despite high participation costs. The question of how UN missions are staffed and maintained assumes added importance in light of recent findings that larger and more diverse missions are more effective at protecting civilians and establishing peace (Hultman, Kathman & Shannon, 2013; Bove & Ruggeri, 2015).

How are peacekeeping missions staffed?

UN peacekeeping missions, along with the mandates and personnel quotas, are established by all members of the UN Security Council. Major powers are often the driving force behind these peacekeeping missions, however, and the initial decision to do so under the auspices of the UN is driven primarily by questions of cost and international legitimacy (Coleman, 2007). The costs of the missions are covered by individual member states, each of whom is assigned a percentage of the annual peacekeeping budget according to the Scale of Assessments (Coleman 2014; see Table I, left panel). Once the mission is established and the level of manpower authorized, soliciting personnel contributions falls to both the Secretary-General and the UN Department of Peacekeeping Operations. On an ostensibly voluntary basis, each potential contributor decides (1) whether to contribute personnel; (2) what type of personnel to contribute (troops or non-combat);³ and (3) how many of each to contribute.

Since the end of the Cold War, the profile of the average UN peacekeeping contributor country has changed dramatically. While much of the burden of Cold War PKOs was shouldered by Western countries,⁴ Bellamy, Williams & Griffin (2004) note that between 1988 and 1994, 41 countries participated in peacekeeping missions for the first time, nearly all of which were developing countries (Bobrow & Boyer, 1997; Lebovic, 2004, 2010; Bove & Elia, 2011).

While peacekeeping scholars have uncovered a variety of factors that make certain countries more likely to contribute, it is our opinion that their importance has been overstated, and that the role of inducements and pressure from powerful UN member states in securing personnel contributions has been overlooked. Below, we review the state of knowledge regarding peacekeeping motivations and the costs of peacekeeping before presenting our argument about the role of foreign aid in the recruitment process.

Motivations for contributing

In the simplest terms, peacekeeping is the private provision of a global, non-excludable public good in the form of greater stability and peace (Diehl, 1993; Bove & Elia, 2011). This public good can be enjoyed by all states, regardless of their role in providing it, and non-contributors cannot be excluded from enjoying the benefits. However, this stylized understanding of the peacekeeping process fails to explain why states with no direct interest in the conflict would incur costs by volunteering their own personnel.

Early peacekeeping literature therefore suggested that peacekeeping participation is better understood as a ‘joint product model’ (Khanna, Sandler & Shimizu, 1998), or the provision of an impure public good (Bobrow & Boyer, 1997). Here, the provision of the public good also produces – as an externality – idiosyncratic private benefits that accrue specifically to those who help provide it. If peacekeeping were a pure public good – if participants received no private benefits – each state’s self-interest would ensure that it was either under-provided or not provided at all (e.g. Olson, 1971). Thus, the existence of peacekeeping collective action must mean that participants are enjoying some private benefits from participating.

Peacekeeping scholars have outlined a number of private benefits that supposedly serve as selective incentives to motivate participation. For instance, many states believe that by contributing, they will earn a reputation as a responsible ‘global citizen’ and/or a regional power broker (Neack, 1995). They may simply take pride in their role as peacekeeping participants and consider it a signal of their commitment to international peace (Axe, 2010; Zaman & Biswas, 2013). Khanna, Sandler & Shimizu (1998) mention the possibility that states may also contribute as part of a path to gain membership of NATO or the European Union. Other governments benefit from the training their militaries receive. They may also select troublesome military units to send overseas (Hesse, 2015). Recently, Kathman & Melin (2016) showed that states increase UN contributions in the wake of coup attempts, and a large literature finds that peacekeeping can improve civil-military relations (see Lundgren, 2018, for a review of this literature). Finally, countries in the neighborhood of a UN peacekeeping mission can benefit from the restoration of regional stability, giving them an obvious incentive to participate (Bobrow & Boyer, 1997). Bove & Elia (2011) and Passmore, Shannon & Hart (2018) also note the country- and region-specific economic and security gains that motivate personnel contributions to peacekeeping missions.

The factor cited perhaps most frequently as a selective incentive is the reimbursement that personnel-contributing governments receive in exchange. The UN in 1974 established a peacekeeping budget (discussed above) with which to finance these missions, to encourage participation, and to reimburse contributing governments for the costs of deployment. The governments of contributing countries maintain their personnel as they normally would, and then are reimbursed according to the UN base rate of $1,410 per soldier per month.⁵

During the peacekeeping expansion in the 1990s, the conventional wisdom was that governments in contributing states could profit under the original monthly reimbursement, given that the rate exceeded what many of them paid to maintain their soldiers (Thakur, 1984; Krishnasamy, 2003; Bellamy & Williams, 2013b). In practice, the UN reimbursement does not cover the full costs of peacekeeping contributions for the participating countries. Moreover, reimbursements are incommensurate with the bargaining leverage that potential contributors hold, and thus are less significant as motivating factors than previously believed. We discuss these costs in detail in the next section.

The costs of contributing

While we do not deny that states enjoy certain benefits from participation, our argument begins from the fact that participation in peacekeeping is, on balance, quite costly to the contributing country in practical terms, contrary to conventional wisdom and a number of scholarly arguments (e.g. Bobrow & Boyer, 1997; Khanna, Sandler & Shimizu, 1998; Gaibulloev et al., 2015). The argument against the supposed profit motive for contributing has been developed and presented convincingly by Coleman (2014) and Coleman & Nyblade (2018), but we will briefly summarize it here.

First, the reimbursement system has been in place since the mid-1970s, but the stark division of labor between wealthy and developing states did not arise until the late 1990s (see Figure 1), just as participation was becoming less financially rewarding. As Coleman & Nyblade (2018) note, the profit-from-reimbursement explanation cannot account for developing states beginning to participate in larger numbers when their ability to reap profits was declining rapidly.

Both Coleman (2014) and Coleman & Nyblade (2018) document a variety of factors which caused the costs incurred by contributing states to increase after the 1990s. The first was the stagnant monthly reimbursement base rate, which remained at $1,028 from 1992 until 2015 (Coleman & Nyblade, 2018: 3). In terms of local purchasing power, the reimbursement rate shrank during this time by 30% to 40% (Coleman, 2014: 15). Furthermore, according to a 2014 UN survey of participating countries, the true monthly cost of deployment – including pre-deployment expenses – was between $1,536 and $1,763 per soldier. Even under the most generous cost estimate, this exceeds even the 2017 rate increase to $1,410 per month.

Additionally, some countries have refused to pay their peacekeeping assessment, leading to chronic financial shortages within the UN Department of Peacekeeping Operations (Bellamy, Williams & Griffin, 2004). The budget is often reliant on voluntary financial contributions from member states to compensate for shortfalls. As a result, reimbursements are typically slow to arrive, if they arrive at all (Coleman, 2014). Contributing countries are therefore asked to assume financial risk up-front with the hope that their reimbursement will arrive eventually.

This also does not account for recent efforts within the UN to enforce minimum standards of personnel quality for peacekeepers, which constitutes an additional burden for troop-contributing countries. The more dangerous and complex missions undertaken in the 2000s by the United Nations often entail tasks that are beyond the capabilities of regular infantry soldiers (Bellamy & Williams, 2013a). While the UN increasingly requires higher-quality personnel and specialists for these missions, the standard reimbursement rate was formulated for low-ranking soldiers. This forces states to sacrifice higher-quality personnel, without a commensurate pay increase, if they wish to contribute.

Peacekeeping missions have also become more complex and dangerous over the past 20 years (e.g. Hultman, Kathman & Shannon, 2014). Rather than simply policing demilitarized zones or managing post-conflict elections, these missions often deploy to active conflicts. In fact, every UN mission since 1999 has been authorized under Chapter VII, which mandates the use of force. Kofi Annan candidly described this shift in 1997: ‘Our job is to intervene: to prevent conflict where we can, to put a stop to it when it has broken out, or […] to contain it and prevent it from spreading’ (quoted in Doyle & Sambanis, 2006). Hultman, Kathman & Shannon (2014) noted the unprecedented 2013 UN Security Council decision to deploy a contingent of 3,000 troops tasked specifically with using force against rebels in the Democratic Republic of Congo. A recent UN report explicitly encourages peacekeepers to leave their bases and take offensive actions to protect themselves (United Nations, 2017). Not only do these missions require better-trained personnel, but they also pose greater risks for the soldiers. Just recently, 15 Tanzanian peacekeepers were killed in a single attack in eastern DRC (UN News, 2017). Leaders in contributing states are vulnerable to the political and financial costs of sending their own personnel abroad to fight and possibly die in conflicts for ambiguous public benefit.

Again, we do not claim that states get no benefit from contributing. Some states likely do benefit at the margins from enhanced international reputations, and the financial gain from personnel reimbursements likely is a motivating factor in some cases (see Coleman & Nyblade, 2018). Rather, we contend that because these benefits are incommensurate with the costs incurred by contributing countries, these factors alone are insufficient to explain how these missions continue to be staffed and deployed. If developing states were motivated to participate by profit, before the late 1990s would have been the ideal time to do it. Yet, this is not what we see. This brings us back to our motivating question: how are UN peacekeeping missions assembled, staffed, and maintained, if participation is so costly for developing countries? We contend that inducements and side-payments in the form of foreign aid from powerful UN member states play a key role in the ability of the UN to secure personnel for peacekeeping missions.

In the following sections, we discuss the use of foreign aid by pivotal states as a supplementary financial incentive – and potential sanction – in order to recruit personnel from low-income countries.

Pivotal states and the recruitment of peacekeepers

The main takeaway from the previous section is that participation in peacekeeping is costly – both politically and financially – relative to the benefits. Given these costs and the collective action problems inherent to peacekeeping operations, it should come as no surprise that the average post-Cold War UN peacekeeping mission suffers from a 21.6% shortfall below authorized personnel levels (Passmore, Shannon & Hart, 2018). In 2011, former Secretary-General Ban Ki-moon lamented that ‘securing the required resources and troops [for UN peacekeeping] has consumed much of my energy. I have been begging leaders to make resources available to us’ (quoted in Bellamy & Williams, 2012). Similarly, the UN has institutionalized efforts – such as the 2000 Brahimi Report and the 2009 New Horizon initiative – to diversify and increase personnel contributions from member states.

In addition, many states find that committing only a handful of personnel to PKOs – so-called ‘token’ contributions – is a low-cost route to the enhanced prestige, political influence, and other reputational benefits that accrue to contributors. This has become such a problem that Coleman (2013) cites tokenism as the main factor inhibiting personnel recruitment for UNPKOs.

In other words, peacekeeping personnel are in high demand. The factors commonly assumed to function as selective incentives are in fact insufficient to attract enough peacekeepers to staff each mission. Moreover, the UN lacks an institutional mechanism to offer additional incentives beyond the troop cost reimbursement, or to punish non-contributors.

So how are peacekeepers recruited, and how are missions maintained as costs to contributors rise? Not much is known about the actual recruitment process, but recent studies have shed considerable light on the bargaining that occurs between so-called ‘pivotal states’ and potential troop-contributing countries. As demonstrated by Henke (2016, 2017), it is these pivotal states that play the dominant role in recruiting personnel, with UN diplomats acting as ‘middle men’, identifying potentially interested countries that are amenable to these bilateral transactions. Pivotal states are countries – often major powers – with strong interests in quickly assembling and deploying peacekeeping forces to conflicts. Pivotal states vary by mission. For instance, France and the UK are coded as pivotal states for several missions in countries with which they have colonial ties; Australia organized missions in East Timor; and the USA has been the pivotal state for missions in Haiti and Darfur. For reasons mentioned above, these same states are unwilling to deploy their own troops but have the financial and political power to persuade developing states to do so instead. In Olson’s collective action framework, pivotal states are ‘political entrepreneurs’, or individual actors willing to pay disproportionate costs to assemble and mobilize large groups to overcome the collective action problem.

Diplomats and officials in potential contributing countries are aware of pivotal states’ preferences to staff missions quickly while avoiding using their own personnel. This, combined with the absence of any mechanism to punish non-participation, gives potential contributors substantial bargaining leverage, enabling them to demand various concessions in exchange for their troop commitments. Henke (2016) highlights this leverage in her case study of recruitment for the UN mission in Darfur, illustrating a process in which diplomats from pivotal states are personally involved in securing contributions for their missions by leaning on diplomats from developing countries, while simultaneously promising favors.

The role of foreign aid

Pivotal states can offer a range of inducements to entice potential contributors to offer their personnel. We focus on one in particular – foreign aid – which, while not mentioned in recent peacekeeping literature, is commonly used as a tool of statecraft by major powers to delegate security-related tasks to smaller states. About the use of foreign aid, (Morgenthau, 1962: 303) writes ‘[T]raditional aid can be understood as a division of labor between two allies who pool their resources, one supplying money, matériel, and training, the other providing primarily manpower’. In essence, aid can be understood as a bribe meant to persuade another country to alter its policies in some way favorable to the donor, and to compensate it for the costs of doing so (see also Bueno de Mesquita & Smith, 2007; Vreeland, 2011, among others). Both sets of states benefit from this division of labor. Pivotal states gain manpower and cooperation from developing countries while keeping their own troops at home; the latter secure foreign aid with which to pursue their domestic goals (e.g. Bueno de Mesquita & Smith, 2007), while also enjoying the other benefits of participation.

We explore the role of foreign aid in UN peacekeeping recruitment in several ways. First, as mentioned above, one of the biggest obstacles to force generation in UN peacekeeping missions is the practice of token contribution, or contributing a small number of personnel to a peacekeeping mission. In fact, token contribution is the most common form of peacekeeping participation – particularly as missions have become more dangerous. Increasing contributions from these states is seen as a critical step toward meeting the manpower needs of future peacekeeping operations. Bellamy & Williams (2013a: 444–445) even specifically recommend using financial inducements to persuade contributors to become major contributors. The idea in targeting these states is to widen the pool of major contributors and ultimately ameliorate the chronic personnel shortage noted by Passmore, Shannon & Hart (2018).

At the same time, much of the manpower for these missions is provided by a handful of major contributors. These states have leverage to make demands of pivotal states in exchange for their contributions. For instance, the United States persuaded the Paris Club to grant Nigeria $18 million in debt relief in exchange for participation in UNAMID (Henke, 2016: 482). At this point, Nigeria was already a well-established major contributor, but was still able to gain substantial concessions for its continued participation. Thus, we should expect major contributors to be plied with even higher levels of aid by the relevant pivotal states. This leads to our first hypothesis,

Hypothesis 1: (a) Token troop contributors in year t−1 will receive more aid from the relevant pivotal state(s) in year t than non-contributors.

(b) Major troop contributors in year t−1 will receive more aid from the relevant pivotal state(s) in year t than token contributors.

Second, we further argue that states incurring casualties in UN peacekeeping operations will require additional compensation as their costs of deployment rise. Troop casualties are financially and politically costly for a government, and may lead a contributing state to become discouraged and cease participating in a particularly dangerous mission. The Burundian government, for example, pays US $50,000 to the family of each soldier killed in action (Moncrieff & Vircoulon, 2017), a significant amount for a developing country. Pivotal states will wish to avoid losing these states’ contributions to their mission, and should respond to casualties with foreign aid as ex post⁶ compensation in order to prevent defections.

Hypothesis 2: Contributing countries will receive more aid from relevant pivotal states in year t as their number of personnel killed in the mission in year t−1 increases.

Our final hypotheses concern the effect of foreign aid on the likelihood and magnitude of participation: are these side-payments successful at inducing personnel commitments to a particular mission? One of the central obstacles donor countries face when assessing aid effectiveness is the difficulty of determining whether a recipient is complying with a quid pro quo. This information asymmetry hinders donors’ ability to place conditions on aid: a donor cannot credibly threaten to withdraw aid for non-compliance if it cannot be readily distinguished from compliance. In this case, however, compliance is observable: personnel in exchange for aid. By under-contributing after agreeing to do otherwise, states jeopardize their aid flows.

A state’s contribution is the outcome of two discrete decisions: the decision to contribute and the size of the contribution. We follow previous studies on peacekeeping contributions (e.g. Bove & Elia, 2011; Kathman & Melin, 2016) and construct separate hypotheses to model this two-stage decision process:

Hypothesis 3: As level of aid from pivotal states in year t−1 increases, the likelihood of a state contributing personnel to the corresponding mission in year t increases.

Hypothesis 4: As the level of aid from pivotal states in year t−1 increases, the number of personnel committed to the corresponding mission in year t increases.

We consider our framework an extension of the joint product model described above. Peacekeeping undoubtedly leads to some private, country-specific benefits for participants. However, we question how much these benefits, many of which are intangible, drive the force generation process. We believe that it would be prohibitively difficult to generate sufficient manpower for UNPKOs were it not for the provision of inducements by pivotal states. Contributing states have significant bargaining leverage vis-à-vis these pivotal states when deciding whether or not to contribute, and we feel that this has been overlooked in previous arguments about peacekeeping participation. In the joint product model, the private benefit is produced along with the public good as part of the same process (Bobrow & Boyer, 1997; Khanna, Sandler & Shimizu, 1998). Our model differs slightly in that both the public good and the often-discussed private benefits would be under-produced without the use of foreign aid as a selective incentive to facilitate the peacekeeping process in the first place. We describe our empirical analyses in the following section.

Empirical analyses

Since the argument pertains to personnel contributions from developing countries, our unit of analysis is the contributor-mission-year between 1971 and 2015 among non-OECD states. Contributor-mission-year is appropriate because we are concerned with the manner in which pivotal states use foreign aid to induce participation in the missions they care about. Evaluating this theory at the country-year level risks over-aggregating pivotal states’ aid allocation and contributors’ mission-specific personnel contributions.⁷

The dependent variable for our first two hypotheses is the total amount of foreign aid received by contributing country i from the pivotal state(s) for a given mission. Since our unit of analysis is mission-contributor-year, this amount will differ across missions depending on the pivotal state(s).⁸

We look only at aid from the pivotal states for each mission, since it is these donor states – as opposed to, say, Iceland or Slovenia – that provide inducements to potential contributors. With occasional exceptions, all of our pivotal states are aid-giving members of the OECD. Data on bilateral aid flows are taken from OECD (2018).⁹

Data on personnel contributions to UN peacekeeping missions for 1990 through 2015 were obtained from the IPI Peacekeeping Database (Perry & Smith, 2013; International Peace Institute, 2017). To aggregate the monthly contribution levels to annual contributions, we use the average of all months for which a state contributed. Data for 1971 to 1989 are original, and were collected by the authors from official UN source documents.¹⁰ Here, each document has been coded up to the latest calendar month for each mission annually.¹¹ Two variables were constructed for each mission-year: Total troops and Total non-combat personnel. The latter figure consists of military police and observers, personnel deployed on the ground but not engaged in hostilities.

Targeting contributing states

To test our hypothesis that pivotal states channel aid toward troop contributors, we create a series of binary indicators classifying non-contributors, token contributors,¹² and major contributors (more than 40 troops) in order to compare aid allocation to each category. We estimate four OLS regressions – one for each significant time period – in which the log of aid from the relevant pivotal state(s) is the dependent variable. In addition to the three categories of contributor, covariates include country population, GDP per capita, infant mortality (taken from World Bank, 2017), and a democracy indicator equal to 1 if the combined Polity score is greater than 6. Each model includes country fixed effects, and the full model includes period fixed effects. Results are presented in Table II.

Rows 1–3 in Table II contain the estimates for each contributor category, with non-contributors as the reference. In Model 1, estimates indicate contributing states do not receive significantly different amounts of aid from non-contributors during the Cold War. However, this changes after the Cold War. Models 2–4 show that both token and major contributors receive more aid than non-contributors throughout the post-Cold War period. Furthermore, the difference between token and major contributors is statistically significant, meaning that major contributors receive significantly more aid than token contributors. These findings support both parts of Hypothesis 1.

Table III displays the predicted changes in foreign aid as a country moves from being a non-contributor to a token contributor, and from there to major contributor status.¹³ Non-contributors that become low-level contributors can expect a subsequent 133% increase in foreign aid from the pivotal state(s) for that mission. Token contributors can expect an even larger increase – 234% – after they become major contributors. Both of these increases are statistically significant at the $p < 0.001$ level.

These findings make sense based on how UN peacekeeping has evolved. As missions expanded in both number and scope during the 1990s, the need to generate manpower became more acute. The pivotal states organizing these missions likely realized that relying upon a handful of countries for the vast majority of peacekeepers was unsustainable. The need to ‘broaden the base’ of major contributors by prodding low-level contributors to become major contributors has thus become a priority for the UN. Both Coleman (2013) and Bellamy & Williams (2013a) speak of the need for a shift in attitudes and policies toward peacekeeping in these countries, and the use of foreign aid to change recipients’ policies is well known. States on the fence about increasing their contributions will find it more difficult to resist such pressure if an aid package is tied to their decision. This dynamic is exemplified in US efforts to assemble the Darfur mission. In addition to debt relief for Nigeria mentioned above, the United States resumed foreign assistance to Thailand, which had been suspended in the

Table II.

Do pivotal UN member states give more aid to troop-contributing countries?

	1971–89	1990–99	2000–15	1990–2015
	Model 1	Model 2	Model 3	Model 4
Non-contributor _t _–1	–	–	–	–
Token contributor _t _–1	2.20	2.40***	0.61**	0.85***
	(2.85)	(0.46)	(0.21)	(0.20)
Major contributor _t _–1	1.12	3.63***	2.03***	2.05***
	(0.89)	(0.51)	(0.21)	(0.20)
ln(GDP pc) _t _–1	1.64**	−0.53	−8.17***	−3.16***
	(0.52)	(0.42)	(0.24)	(0.15)
ln(Population) _t _–1	14.37***	−5.89***	−11.48***	−2.69***
	(1.11)	(1.21)	(0.44)	(0.33)
Infant mortality _t _–1	−0.07***	−0.07***	0.00	−0.00
	(0.01)	(0.02)	(0.01)	(0.00)
Democracy _t _–1	0.96*	0.14	1.03***	0.12
	(0.39)	(0.31)	(0.17)	(0.13)
(Intercept)	−188.18***	84.85***	231.80***	69.06***
	(15.36)	(15.50)	(6.22)	(4.74)
Country fixed effects	✓	✓	✓	✓
Decade fixed effects				✓
R²	0.57	0.28	0.31	0.26
N	5,357	18,196	44,578	62,774

Standard errors are in parentheses. Significance levels: ***p < 0.001, **p < 0.01, *p < 0.05.

Table III.

Foreign aid and troop contribution size

Change in contributor status	Predicted aid increase	95% CI
Non-contributor ⇒ Token contributor	+134%	[59%–242%]
Token contributor ⇒ Major contributor	+234%	[97%–467%]

aftermath of a military coup, in exchange for their deployment (Henke, 2016).

The various US State Department aid programs that began in the 1990s also demonstrate this pattern of using foreign assistance to boost capability and willingness to participate in peacekeeping missions. The original emphasis of these programs was on African countries, although the current program – Global Peace Operations Initiative – has expanded to include 51 countries from around the world (Serafino, 2009).

At the same time, ongoing peacekeeping missions would suffer an even more severe personnel shortage if a major contributor underwent a sudden peacekeeping policy shift. Major contributors thus have greater leverage to demand aid concessions from the relevant pivotal states. This is reflected in numerous examples of contributing states using their peacekeeping participation as bargaining chips when negotiating with major powers over aid allocation. Burundi, for instance, sought aid from donors in exchange for large contributions of troops to regional peacekeeping missions in order to help in its recovery from a civil war in the mid-2000s. Bujumbura has successfully used its peacekeeping contributions as leverage to negotiate for continued foreign assistance despite donor threats to cut aid over concerns about governance and human rights (Hesse, 2015: 335–336). Other regional powers, such as Rwanda and Ethiopia, have received similar treatment in exchange for robust peacekeeping contributions (Fisher, 2012). The African Peacekeeping Rapid Response Partnership (APRRP), another US State Department program initiated in 2015, focuses on eliciting more rapid deployments to regional missions from six of the top African peacekeeping participants (US Department of State, 2018).

We consider these findings to be strong evidence in support of our argument that pivotal states wield foreign aid as an instrument of statecraft to encourage greater participation in UN missions, and that major contributors use their deployments as leverage to extract aid concessions from donors. This supports the link between the strategic use of aid as a selective incentive and UN peacekeeping force generation.

Table IV.

UN peacekeeping fatalities and foreign aid from pivotal states

	1971–89	1990–99	2000–15	1990–2015	1990–2015
	Model 1	Model 2	Model 3	Model 4	Model 5
ln(Peacekeeper deaths) _t _–1	1.92	1.72**	1.37***	1.51***	1.55***
	(1.14)	(0.66)	(0.28)	(0.27)	(0.26)
ln(GDP pc) _t _–1	−3.75	−5.09*	−13.89***	−11.37***	−10.48***
	(11.20)	(2.41)	(0.72)	(0.55)	(0.61)
ln(Population) _t _–1	7.03	0.89	−21.42***	−6.38***	−4.10**
	(26.36)	(6.16)	(1.86)	(1.36)	(1.43)
Infant mortality _t _–1	−0.15	0.03	−0.02	0.02	0.02
	(0.25)	(0.07)	(0.02)	(0.02)	(0.02)
Democracy _t _–1	−1.62	−0.45	1.28***	0.26	−0.08
	(2.71)	(1.79)	(0.34)	(0.29)	(0.29)
(Intercept)	−46.64	39.09	473.29***	193.04***	155.52***
	(457.54)	(78.86)	(31.63)	(19.80)	(21.49)
Country fixed effects	✓	✓	✓	✓	✓
Decade fixed effects					✓
R²	0.77	0.31	0.35	0.29	0.31
No. obs.	56	1,323	6,665	7,988	7,988

Standard errors are in parentheses. Sample includes only states that contributed in year t−1. Significance levels: ***p < 0.001, **p < 0.01, *p < 0.05.

Aid as ex post compensation

Our second hypothesis is that pivotal states should further compensate countries that incur greater costs during peacekeeping missions to prevent them from reducing their contributions. It is costly for governments when their personnel are killed overseas. Furthermore, UN missions vary widely in terms of the level of risk associated with them. Troops deployed to Mali as active participants in an ongoing conflict are surely in greater danger than those monitoring a 40-year-old ceasefire in Cyprus. Accordingly, just as they must recruit states to contribute manpower at the outset, pivotal states must dissuade contributors that have suffered personnel losses from defecting from missions they deem too costly or dangerous. This is the intuition behind Hypothesis 2. We borrowed from Henke (2019) information on the number of troop and non-combat personnel deaths in each UN mission by contributing country, and incorporated that into our contributor-mission-year data from 1970 to 2015.

To test Hypothesis 2, we present a set of linear models in Table IV in which the dependent variable is, again, aid received from the corresponding pivotal state in mission-year t. Our primary independent variable, annual fatalities incurred by mission, is lagged one year. We use the same aid-relevant covariates from the previous section. Each model includes country fixed effects, and the models estimated on the full post-Cold War sample include decade fixed effects.¹⁴

As expected, Table IV shows that states suffering personnel fatalities in UN missions do not receive significantly more aid from pivotal states during the Cold War. This changes after 1990, however, when the division of labor began to grow, enabling developing countries to demand concessions from pivotal donor states in exchange for costs incurred during peacekeeping operations. This is borne out by the significant coefficient estimates for Peacekeeper deaths in each post-1990 period and the full post-Cold War sample (Models 2–5).¹⁵

To determine whether pivotal states compensate contributing states for losses of troops at different rates than for non-combat personnel losses, we further disaggregated the UN fatalities data and estimated several additional models, the results of which are presented in Table V. The table contains two estimations for each time period – one each to determine the effect of troop- and non-combat personnel fatalities endured on aid

Table V.

UN peacekeeping fatalities and foreign aid from pivotal states: Troops vs non-combat personnel deaths

	1971–89		1990–99		2000–15		1990–2015
	Model 1	Model 2	Model 3	Model 4	Model 5	Model 6	Model 7	Model 8
ln(Troop deaths) _t _–1	1.92		1.99**		0.82**		1.18***
	(1.14)		(0.71)		(0.31)		(0.29)
ln(Police/observer deaths) _t _–1		N/A		0.59		3.76***		3.20***
				(1.83)		(0.71)		(0.68)
ln(GDP pc) _t _–1	−3.75	−5.41	−5.14*	−4.72	−13.91***	−13.86***	−10.49***	−10.48***
	(11.20)	(11.40)	(2.41)	(2.41)	(0.72)	(0.72)	(0.61)	(0.61)
ln(Population) _t _–1	7.03	−1.66	1.04	0.88	−21.23***	−21.27***	−3.91**	−3.83**
	(26.36)	(26.41)	(6.16)	(6.18)	(1.86)	(1.85)	(1.43)	(1.43)
Infant mortality _t _–1	−0.15	−0.24	0.03	0.05	−0.02	−0.02	0.02	0.02
	(0.25)	(0.25)	(0.07)	(0.07)	(0.02)	(0.02)	(0.02)	(0.02)
Democracy _t _–1	−1.62	−0.40	−0.52	−0.30	1.28***	1.27***	−0.08	−0.11
	(2.71)	(2.66)	(1.79)	(1.80)	(0.34)	(0.34)	(0.29)	(0.29)
(Intercept)	−46.64	97.01	37.77	35.17	470.40***	470.61***	153.25***	152.17***
	(457.54)	(459.23)	(78.81)	(79.06)	(31.67)	(31.60)	(21.51)	(21.48)
Country fixed effects	✓	✓	✓	✓	✓	✓	✓	✓
Decade fixed effects							✓	✓
R²	0.77	0.75	0.31	0.31	0.35	0.35	0.31	0.31
N	56	56	1,323	1,323	6,665	6,665	7,988	7,988

Significance levels: ***p < 0.001, **p < 0.01, *p < 0.05. Standard errors are in parentheses. Sample includes only states that contributed in year t–1.

received from the relevant pivotal states. Personnel fatalities incurred by contributing countries are not significantly related to increases in aid allocation during the Cold War period or during the 1990s. Troop fatalities begin to significantly influence aid receipts beginning in the 1990s, although non-combat fatalities remain insignificant.

After the late 1990s, the shift of the manpower burden onto developing countries accelerates (again, see Figure 1). As we would expect theoretically, we find that in the post-1999 subsample (Models 5 and 6) and the full post-Cold War sample (Models 7 and 8), contributors suffering more fatalities of both types receive significantly more foreign aid from pivotal states the following year. Figure 2 displays the substantive effects of increases in both types of personnel fatalities on the expected amount of aid received.¹⁶

That contributing countries appear to be compensated for personnel fatalities, but only beginning after the Cold War, supports our argument. As UN peacekeeping became more ambitious and the demand for manpower grew, the major powers most invested in assembling certain PKOs began to use foreign aid as a tool to overcome the collective action problem among developing states. Moreover, pivotal states apparently recognize the risks inherent in participating in more violent, costly conflicts, and compensate countries for losses they incur in an effort to maintain the cohesiveness of these coalitions. These findings mean that, in addition to using aid as an incentive to facilitate and reward contributions, pivotal states also further compensate personnel losses ex post to prevent defection. Together, our findings shed significant light on the methods used by powerful UN member states to recruit personnel, and on why countries continue participating in increasingly violent UN PKOs, given the fact that no formal mechanism exists to compensate countries for losses incurred, or to punish defections or non-participation.

Does aid increase personnel contributions?

Our final hypothesis predicts that countries will respond to aid from pivotal states by participating more frequently and contributing more personnel. This necessitates a two-stage hurdle model in which the dependent variables are (1) whether a state contributes any personnel at all in a given year, and (2) a count of personnel deployed. Specifically, we use the hurdle model described in Zeileis, Kleiber & Jackman (2008). Unlike zero-inflated models, it assumes that zeros are the result

Figure 2.

Substantive effects of personnel fatalities on aid received

of a state’s decision not to contribute (Cameron & Trivedi, 2013). We believe this is an appropriate assumption, similar to previous studies of UN personnel contributions (e.g. Bove & Elia, 2011; Kathman & Melin, 2016).

Independent variables

Our main independent variable in both stages is the log of aid received from the pivotal states for each mission. Logged GDP per capita and population are taken from the World Bank. A dummy variable for contiguity to the mission is also included (Stinnett et al., 2002).

We also construct a count of the total number of ongoing peacekeeping missions to account for the opportunity to contribute. Gaibulloev et al. (2015) argue that increasing numbers of operations should increase the overall country supply, while Bove & Elia (2011) argue that increasing operations should decrease the likelihood and size of contributions per operation due to troop constraints.¹⁷ We also include the sum of the total number of peacekeeping missions to which a state has contributed over the previous five years. This variable accounts for institutional inertia of participation, the fact that participation in UN operations entails training and experience for the troops involved, the internalization of norms and benefits, and the troop interoperability that accrues to frequent participants. Finally, to account for the possibility that democracies may be more likely to contribute to PKOs (e.g. Lebovic, 2004), we include a democracy indicator equal to 1 if the combined Polity score is greater than 6 (Marshall, Gurr & Jaggers, 2016). Where appropriate, covariates are lagged one year.

Foreign aid and the decision to contribute

Our findings are reported in Table VI. As in our analyses above, we account for the evolving nature of UN peacekeeping by estimating separate models on each notable time period in the data.¹⁸ Findings regarding the initial decision to contribute personnel are shown in the lower half of Table VI. Foreign aid from pivotal states is a positive and highly significant determinant of the decision to contribute both types of peacekeeping personnel. This is the case across all post-1990 time periods and in the full sample, lending support to Hypothesis 3. Consistent with past studies of PKO contributions (e.g. Lebovic, 2004; Ward & Dorussen, 2016; Gledhill & Duursma, 2019), we also find that democracies, across all time periods, are more likely to contribute both types of personnel.

Table VI.

Aid from pivotal states and personnel contributions: Results of a hurdle model

	2000–15		1990–2015		1971–2015
	Model 1	Model 2	Model 3	Model 4	Model 5	Model 6
DV:	Troops	Non-combat	Troops	Non-combat	Troops	Non-combat
Size of contribution
Intercept	−1.42	3.37***	0.73	${4.37}^{* * *}$	${2.52}^{* *}$	${4.35}^{* * *}$
	(1.37)	(0.45)	(0.95)	(0.40)	(0.79)	(0.40)
ln(Aid from pivotal states) _t _–1	${0.03}^{* * *}$	${0.03}^{* * *}$	${0.02}^{* *}$	${0.04}^{* * *}$	${0.02}^{* *}$	${0.04}^{* * *}$
	(0.01)	(0.00)	(0.01)	(0.00)	(0.01)	(0.00)
ln(GDP pc) _t _–1	$- {0.20}^{* * *}$	$- {0.40}^{* * *}$	$- {0.23}^{* * *}$	$- {0.36}^{* * *}$	$- {0.24}^{* * *}$	$- {0.36}^{* * *}$
	(0.06)	(0.02)	(0.05)	(0.02)	(0.05)	(0.02)
ln(Population) _t _–1	${0.28}^{* * *}$	${0.09}^{* * *}$	${0.22}^{* * *}$	${0.07}^{* * *}$	${0.21}^{* * *}$	${0.07}^{* * *}$
	(0.04)	(0.02)	(0.03)	(0.02)	(0.03)	(0.02)
No. of ongoing PKOs	0.01	$- {0.06}^{* * *}$	0.01	$- {0.11}^{* * *}$	$- {0.06}^{* * *}$	$- {0.11}^{* * *}$
	(0.04)	(0.02)	(0.02)	(0.01)	(0.02)	(0.01)
Contiguous UNPKO	${0.65}^{*}$	${0.27}^{*}$	${0.51}^{*}$	${0.27}^{*}$	${0.51}^{*}$	${0.27}^{*}$
	(0.27)	(0.14)	(0.25)	(0.13)	(0.24)	(0.13)
Recent UNPKO participation	${0.02}^{* * *}$	${0.03}^{* * *}$	${0.02}^{* * *}$	${0.03}^{* * *}$	${0.02}^{* * *}$	${0.03}^{* * *}$
	(0.00)	(0.00)	(0.00)	(0.00)	(0.00)	(0.00)
Democracy _t _–1	$- {0.27}^{*}$	$- {0.36}^{* * *}$	$- {0.35}^{* *}$	$- {0.33}^{* * *}$	$- {0.30}^{* *}$	$- {0.33}^{* * *}$
	(0.13)	(0.05)	(0.12)	(0.05)	(0.11)	(0.05)
Log(theta)	$- {4.52}^{* * *}$	$- {1.98}^{* * *}$	$- {3.96}^{* * *}$	$- {1.96}^{* * *}$	$- {3.64}^{* * *}$	$- {1.95}^{* * *}$
	(0.92)	(0.09)	(0.48)	(0.08)	(0.35)	(0.08)
Likelihood of contributing
Intercept	$- {3.33}^{* * *}$	$- {3.52}^{* * *}$	$- {3.73}^{* * *}$	$- {4.88}^{* * *}$	$- {5.17}^{* * *}$	$- {5.88}^{* * *}$
	(0.39)	(0.28)	(0.32)	(0.24)	(0.28)	(0.22)
ln(aid from pivotal states) _t _–1	${0.04}^{* * *}$	${0.03}^{* * *}$	${0.04}^{* * *}$	${0.03}^{* * *}$	${0.04}^{* * *}$	${0.03}^{* * *}$
	(0.00)	(0.00)	(0.00)	(0.00)	(0.00)	(0.00)
ln(GDP pc) _t _–1	$- {0.14}^{* * *}$	$- {0.14}^{* * *}$	$- {0.10}^{* * *}$	$- {0.09}^{* * *}$	$- {0.11}^{* * *}$	$- {0.09}^{* * *}$
	(0.02)	(0.01)	(0.02)	(0.01)	(0.02)	(0.01)
ln(population) _t _–1	${0.08}^{* * *}$	${0.06}^{* * *}$	${0.10}^{* * *}$	${0.09}^{* * *}$	${0.11}^{* * *}$	${0.10}^{* * *}$
	(0.01)	(0.01)	(0.01)	(0.01)	(0.01)	(0.01)
No. of ongoing PKOs	$- {0.09}^{* * *}$	0.00	$- {0.11}^{* * *}$	${0.02}^{* * *}$	$- {0.03}^{* * *}$	${0.07}^{* * *}$
	(0.01)	(0.01)	(0.01)	(0.01)	(0.01)	(0.01)
Contiguous UNPKO	${0.28}^{* *}$	−0.16	${0.24}^{*}$	$- {0.18}^{*}$	${0.20}^{*}$	$- {0.18}^{*}$
	(0.10)	(0.09)	(0.10)	(0.08)	(0.09)	(0.08)
Recent UNPKO participation	${0.06}^{* * *}$	${0.06}^{* * *}$	${0.06}^{* * *}$	${0.06}^{* * *}$	${0.06}^{* * *}$	${0.06}^{* * *}$
	(0.00)	(0.00)	(0.00)	(0.00)	(0.00)	(0.00)
Democracy _t _–1	${0.29}^{* * *}$	${0.16}^{* * *}$	${0.31}^{* * *}$	${0.14}^{* * *}$	${0.32}^{* * *}$	${0.15}^{* * *}$
	(0.05)	(0.03)	(0.04)	(0.03)	(0.04)	(0.03)
AIC	44,556.36	72,686.31	53,358.33	87,372.48	54,888.92	87,658.15
Log Likelihood	-22,261.18	-36,326.16	-26,662.16	-43,669.24	-27,427.46	-43,812.07
N	44,718	44,718	62,032	62,032	67,008	67,008

Standard errors are in parentheses. Significance levels: ***p < 0.001, **p < 0.01, *p < 0.05.

Foreign aid and size of contribution

The results of the count models are displayed in the top half of Table VI. These findings support Hypothesis 4, which proposes that the number of personnel contributed rises with the amount of aid received. Specifically, we find that the effect of aid receipts from pivotal states on the number of both troops and non-combat personnel allocated to the relevant mission is statistically significant and positive for all post-1989 time periods and in the full sample. Overall, findings suggest that states are responsive to the use of aid as a financial incentive to contribute, which supports the intuition behind our argument.

Figure 3.

Effect of aid from pivotal states on personnel contributions

The negative and significant estimate for Ongoing PKOs is also worth discussing. This finding conflicts with Gaibulloev et al. (2015), but aligns with Kathman & Melin (2016), who use a count model similar to ours. Substantively, this means that as the number of ongoing PKOs increases, the average country contribution decreases. Although not a direct test of the reimbursement-for-profit argument, we take this as evidence that is inconsistent with it. If states were motivated by personnel reimbursements, we would not expect to find a negative coefficient estimate for this variable.

Finally, we find that while democracies are more likely to contribute, the sizes of their contributions are significantly smaller than those of non-democracies. This finding holds across each of our time periods for both personnel types. Recently, Gledhill & Duursma (2019) have arrived at similar conclusions. Together, these findings suggest that democracies are increasingly likely to be token contributors to UN PKOs, participating frequently but in smaller numbers, while non-democracies do more of the heavy lifting. This is particularly striking because our sample includes only non-OECD countries, meaning that it is not driven by small contingents from Western democracies since the mid-1990s.

Substantive effects

The findings in Table VI support Hypothesis 4, which suggests that states will respond to foreign aid from pivotal states by increasing the size of their deployments. This is also consistent with anecdotal evidence of major powers using inducements and coercion to assemble peacekeeping missions. Figure 3 further explores this hypothesis by plotting the overall expected values as we increase the amount of aid received from the relevant pivotal states over its full range. Democracy is set to its median value, while all other variables are held at their mean.

The plot on the left side of Figure 3 shows the predicted number of non-combat personnel deployed based on the coefficients in even-numbered models in Table VI across the full range of aid values. These are the effects of aid on the expected number of personnel from the average country in a particular mission. The effect of aid appears to be approximately equal in each of the three time periods, although the predicted personnel levels vary a bit – the expected non-combat personnel per mission is lowest in the full sample and highest after 1999.

The substantive effect of aid on the expected number of deployed troops per mission, shown in the right side of Figure 3, is similar. Moving from no aid to the median amount increases the expected troop contribution from 1.3 to 2.9, a 123% increase. Contributors in the 75th percentile of aid received can be expected to contribute 3.74 troops to that mission, an additional 29% increase.

Note that the expected values are low for both personnel types. This is because the modal country contributes zero personnel, which pulls the expected value downward. If we consider only contributors, the values would be approximately eight times larger, but the slopes of the lines would be similar. The discrepancy between levels of troops and non-combat personnel stems from the fact that there are far fewer non-combat personnel than troops deployed to any given mission.

Conclusion

This article sought to explain how the United Nations recruits personnel to staff its peacekeeping operations. Earlier studies of peacekeeping personnel contributions relied heavily upon reputational benefits and the UN deployment reimbursement to explain high levels of participation from developing states. We build on recent research on UN peacekeeping force generation and argue that there is more to the story than a group of states voluntarily lending their soldiers out in exchange for international goodwill and a small reimbursement.

The acute demand for manpower in recent UN missions gives potential contributors significant bargaining leverage with which to demand financial concessions in exchange for their participation. In turn, major powers are often heavily invested in staffing certain missions, but also have strong incentives not to do so with their own personnel. We compile multiple layers of new evidence that major powers with interests in establishing particular missions allocate foreign aid strategically as an inducement to persuade recipient countries to contribute more manpower to these operations, and to continue participating even when doing so becomes costly.

These findings are significant in both theoretical and practical terms. For scholars studying international organizations, we shed light on one of the methods used by the United Nations to compensate for the rising costs of accomplishing one of its most important tasks. We provide an answer to the question of why developing states participate despite climbing costs. This has important practical implications for international security, as UNPKOs continue to play prominent roles in conflicts, and recent findings show that larger UN missions are more effective at protecting civilians and establishing peace (Hultman, Kathman & Shannon, 2013).

We also show that major powers have the ability and resources to persuade smaller states to participate in the pursuit of their own narrow security interests through the distribution of foreign aid. This suggests some potential avenues for future research investigating the potential for foreign aid (or other types of side payments) to facilitate large-scale collective action on a wide range of issues of global interest, from human rights treaties to compliance with environmental agreements.

Footnotes

Replication data

The Online appendix, datasets, and replication files for the analyses in this article can be found at .

Acknowledgements

The authors would like to thank Alex Braithwaite, Paul Diehl, Marina Henke, Jim Lebovic, Paul Williams, and the reviewers for helpful suggestions and feedback. We are also grateful to Michael Allen, Michael Flynn, and Carla Martinez Machain for organizing an excellent panel on military deployments at ISA 2017.

ORCID iD

Andrew Boutton

Notes

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