Abstract
Five years of implementing the 2001 Nuclear Posture Review have led to modest changes in the composition and disposition of U.S. nuclear forces. Slow reductions continue under the 2002 Moscow Treaty, also known as the Strategic Offensive Reductions Treaty (SORT), and more are expected in the next couple of years. Yet ambitious plans have emerged to design, develop, and deploy a new generation of nuclear warheads and to acquire new ballistic missiles, submarines, and bombers.
As of January 2007, the U.S. stockpile contains nearly 10,000 nuclear warheads. This includes about 5,736 active/operational warheads: 5,236 strategic warheads and 500 nonstrategic warheads (see “The U.S. Arsenal,” p. 80). Approximately 4,230 additional warheads are held in the reserve or inactive/responsive stockpiles or awaiting dismantlement. Under plans announced by the Energy Department in June 2004, the stockpile is to be cut “almost in half” by 2012 (see “U.S. Nuclear Reductions,” September/October 2004 Bulletin).
We estimate that this will leave approximately 6,000 warheads in the total stockpile, including the maximum of 1,700-2,200 “operationally deployed” strategic warheads specified by SORT. The 4,000 warheads scheduled for retirement will be gradually dismantled at the Pantex Plant in Texas.
The need for Complex 2030 is debatable. NNSA officials have testified before Congress that the nuclear weapons in the current stockpile are safe and reliable, and many experts believe that building modified or entirely new warheads would create, rather than reduce, uncertainties.
This year the Pentagon will begin retiring 50 Minuteman III missiles, as specified by the 2006 Quadrennial Defense Review. No announcement has been given about where the cut will be made, but a likely candidate is the 341st Space Wing at Malmstrom Air Force Base (AFB), Montana, which has 50 missiles more than the other two wings.
Coinciding with these changes, the air force will begin to reduce (download) the number of warheads carried on each Minuteman III to meet the SORT limit of no more than 2,200 operationally deployed strategic warheads by 2012. The Pentagon announced in February 2006 that it had “removed hundreds of warheads from deployed Minuteman III” ICBMs, but this appears to have referred to an earlier download completed in December 2001 in compliance with START. A new download is anticipated to occur in connection with the W62-W87 swap as part of an overall U.S. reduction in strategic warheads to 3,500-4,000 by 2007.
An earlier plan to convert all Minuteman III missiles to a single-warhead configuration appears to have been revised with the abandonment of the START II agreement. Instead, the future 450-missile force will carry 500 warheads, with another 300 in reserve.
Four Minuteman III missile tests were launched in 2006 from Vandenberg AFB, California. The missiles test-launched on February 16 and April 7 each carried a single, unarmed reentry vehicle; those test-launched on June 14 and July 20 each carried three unarmed reentry vehicles. The February and June tests flew to the normal range of 7,725 kilometers (4,800 miles). The July launch flew 6,760 kilometers (4,200 miles), and the April launch flew to an “extended range” of 8,200 kilometers (5,100 miles). The purpose of the longer flight, according to Air Force Space Command, was to test the Minuteman III at a range more compatible with actual strike plans. The February launch was a verification test of the W87/Mk-21 SERV warhead.
THE U.S. ARSENAL
ACM: advanced cruise missile; ALCM: air-launched cruise missile; ICBM: intercontinental ballistic missile; MIRV: multiple independently targetable reentry vehicle; SLCM: sea-launched cruise missile; SLBM: submarine-launched ballistic missile.
Conversion of the Henry Jackson and the Alabama to Trident II D5 SLBMs will be completed in 2007 and 2008, respectively, bringing to 14 the number of SSBNs capable of carrying D5s.
The first figure is the aircraft inventory, including those used for training, testing, and backup. The second figure is the primary mission aircraft inventory, the number of operational aircraft assigned for nuclear and/or conventional missions.
The large pool of bombs and cruise missiles allows for multiple loading possibilities, depending upon the mission.
The air force issued a Mission Need Statement in 2002 for a new ICBM that would be introduced in 2018. In 2006, more than $10 million was earmarked for studies to define the required capabilities and to set milestones.
Coinciding with the retirement of the Trident I C4 SLBM in 2005, most of the Pacific-based SSBNs have been upgraded to carry the newer and more accurate Trident II D5 SLBM. Two SSBNs in the fleet remain to be converted; the Henry Jackson will be completely converted this year, the Alabama in 2008. The D5 has considerably greater range and accuracy than the C4 and also carries the W88, the highest-yield ballistic missile warhead in the U.S. arsenal.
The upgrade to the Trident II D5 in the Pacific “enhances system accuracy, payload, and hard-target capability,” according to Rear Adm. Charles B. Young, director of the navy's Strategic Systems Program, “thus improving our available responses to existing and emerging Pacific theater threats.”
The navy decided to homeport most of its 14 SSBNs at the Naval Submarine Base in Bangor, Washington, to increase coverage of targets in China, according to navy officials. The SSBNs also target Russia and North Korea.
Besides the W88, D5 missiles also carry the 100-kiloton W76 warhead, which is being enhanced with the new MC4700 arming and fuzing subsystem to give it a groundburst capability for the first time, making it more lethal against more targets. The modified warhead is designated the W76-1, and the new reentry vehicle is the Mk-4A. The first production unit W76-1/Mk-4A is expected to be delivered to the navy in September 2007.
Lockheed Martin developed an “Accuracy Adjunct” for the W76-1/Mk-4A warhead, providing it with “GPS-like accuracy.” Congress refused to fund this program, but work on it continues nonetheless. In March 2005, the sub Tennessee launched a D5 missile equipped with an unarmed reentry vehicle fitted with the Accuracy Adjunct. A navy admiral told us: “I had GPS signal all the way down and could steer it.” The test was significant because the D5 had the shortest trajectory ever flown by a U.S. SLBM–2,200 kilometers (1,370 miles)–with the warhead impacting just 12-13 minutes after launch.
The Accuracy Adjunct technology is also essential if the navy deploys conventional warheads on its SLBMs. A Pentagon proposal to manufacture 96 conventional warheads for deployment on D5 missiles alongside nuclear-armed missiles failed to secure funding from Congress, which instead asked the Pentagon to study the implications of mixing nuclear and conventional weapons on SSBNs.
Procurement of the original Trident II D5 missile ended in 2006. Beginning in 2008, the navy will begin producing a modified D5. A total of 108 missiles are planned through 2011, at a cost of more than $4 billion, with initial deployment planned for 2013. The modified D5s will arm the Ohio-class SSBNs for the rest of their service lives, which have been extended from 30 years to 44 years. The oldest sub is scheduled to retire in 2029, at which point a new SSBN class is planned to become operational.
The first of four older Ohio-class SSBNs that are being converted to nuclear-powered cruise missile submarines (SSGNs) entered service at Bangor's Naval Submarine Base in late 2006. All four subs are expected to be operational by 2008, two in the Pacific and two in the Atlantic. Each submarine will carry as many as 154 advanced Tomahawk sea-launched cruise missiles. The navy also hopes to equip the SSGNs with conventionally armed (and not yet built) submarine-launched intermediate-range ballistic missiles (SLIRBMs). The SLIRBM is designed to deliver a conventional payload to targets more than 1,770 kilometers (1,100 miles) away within 10-15 minutes of launch. The program envisions fitting multiple SLIRBMs inside each SSGN missile tube.
The air force is upgrading both bombers to improve their communications with the National Command Authorities throughout all stages of a nuclear war and to improve targeting flexibility. (For more information, see “U.S. Nuclear Forces, 2006,” January/February 2006 Bulletin.)
B-2 and B-52 aircraft can carry various nuclear bombs: the B61-7 strategic bomb, which has multiple yield options up to 360 kilotons (sometimes referred to as “dial-ayield”) and whose first refurbished production unit was delivered in June 2006; the B61-11 “bunker-buster,” a B61-7 with features designed to allow it to penetrate up to 6 meters (20 feet) underground before detonating (the first refurbished B61-11 is scheduled for delivery in January 2007); and the B83, a high-yield strategic bomb with variable yield options up to 1.2 megatons that is designed for high-speed, low-altitude delivery against hard targets such as the irregular, reinforced concrete surface of an ICBM silo.
The B-52 is also capable of carrying advanced cruise missiles (ACMs) and air-launched cruise missiles (ALCMs), both of which are undergoing service life extension programs to prolong them through 2030. The ACM has a range of more than 3,200 kilometers (2,000 miles); the ALCM has a slightly shorter range of more than 2,400 kilometers (1,500 miles). Both use the W80-1 warhead with variable yield options up to 150 kilotons. A modified warhead for the missiles, the W80-3, is scheduled for delivery in 2008.
A program to extend the service life of the W80 warhead has been suspended, though it might resume sometime in the next decade. As a result, a decision to retire some W80s might be taken in the near future.
The air force continues to study options for a next-generation nuclear cruise missile, including the possibility of a joint enhanced cruise missile, deliverable from any leg of the triad, with a nuclear payload and longer range to support global strike missions against “targets deep within future high threat anti-access environments,” according to air force documents.
Eight bases in six European countries host as many as 400 B61-3 and -4 gravity bombs for delivery by various U.S. and NATO aircraft. Additional tactical bombs are in reserve status stored at Kirtland AFB, New Mexico, and Nellis AFB, Nevada. The 4th Fighter Wing at Seymour Johnson AFB, North Carolina, also has a nuclear strike mission in support of overseas contingencies. The 27th Fighter Wing at Cannon AFB, New Mexico, might have lost its nuclear mission.
U.S. delivery aircraft include the F-16C/D Fighting Falcon and F-15E Strike Eagle. NATO aircraft that are assigned nuclear missions include U.S.-supplied F-16s and German and Italian Tornado bombers. Under current air force planning, a portion of the F-35 Joint Strike Fighter force will have nuclear capability from 2012.
Most U.S. attack submarines (SSN) were credited with some nuclear capability during the Cold War, but today most SSNs do not have nuclear missions. However, nuclear Tomahawk missiles could be redeployed in 30 days. We estimate that no more than 12 SSNs have a nuclear capability. TLAM/Ns are earmarked for deployment on selected Los Angeles-class, improved Los Angeles-class, and Virginia-class SSNs. An estimated 320 TLAM/Ns are stored at the Strategic Weapons Facilities at Bangor and at King's Bay, Georgia, along side strategic weapons for the SSBNs.
Yet a stockpile transformation overview that we discovered on the website of the Office of the Deputy Assistant Secretary of Defense for Nuclear Matters in 2005 listed up to four types of RRWs. Congressional staffers complained to the Nuclear Weapons and Materials Monitor: “We don't have an accepted feasibility design yet for RRW, much less four types.” A joint Defense-Energy interim RRW report submitted to Congress in March 2006 presented an indefinite stockpile plan that included only RRWs but forecast
a NWC “decision on a single RRW design concept.” And, in August, the NNSA stated that its long-term strategy is to transform the nuclear stockpile into “an all RRW-stockpile” around 2030.
Complicating an already complex issue, the RRW Program is competing with various life extension programs already under way to improve longevity of existing warhead types. If an ambitious RRW Program materializes, it would either cancel or reduce the number of warheads that were scheduled to undergo life extensions, namely the W76, W78, and W80 warheads and the B61 bomb.
U.S. stockpile
Warhead type to be fully dismantled.
Warhead type to be partially dismantled.
After more than 10 years and nearly $2 billion, small-scale plutonium pit production is still being “reestablished” at Los Alamos National Laboratory. The lab's TA-55 facility has produced 12 “certifiable” W88 pits since 2003 and plans to make 10 more in 2007; the goal is to be able to manufacture 10 W88 pits per year from 2008 to 2014.
Plans under Complex 2030 call for a consolidated plutonium center (CPC) that would perform R&D and manufacture as many as 125 pits per year. A CPC would also serve to consolidate special nuclear material (predominately plutonium and uranium 235) at fewer sites. Potential CPC locations include Los Alamos, the Nevada Test Site, the Pantex Plant, the Y-12 nuclear complex in Tennessee, and the Savannah River Site in South Carolina.
Plans for a new tritium production facility have been dropped; instead, the Bush administration plans to use civilian power reactors to produce tritium for nuclear weapons, a practice that violates the spirit of the Nuclear Non-Proliferation Treaty. The first “civilian-produced” tritium for use in nuclear weapons will be extracted in September 2007.
Warhead dismantlement at Pantex slowed in recent years to approximately 100 warheads per year–compared with rates of 1,000-1,500 during some years in the 1990s–because life extension programs for operational warheads have taken priority. However, in promoting Complex 2030, the Bush administration announced in April 2006 that it will expedite dismantlement, with completion scheduled for 2023 instead of 2034. Assuming that approximately 4,000 warheads will be retired (to meet SORT goals), this translates into a dismantlement rate of about 250 warheads per year for the next 16 years–still far slower than previous rates.
“Accelerated warhead dismantlements help to assure other nations we are not building up our stockpile,” Deputy Secretary of Energy Clay Sell told Congress. This assurance would be strengthened, however, if the government reversed a 1999 directive that keeps the number of dismantled warheads secret and instead made annual numbers public.