Reduce the Size of the Nuclear Triad

The United States’ nuclear deterrence strategy, developed during the Cold War, is built around the strategic nuclear triad, which comprises intercontinental ballistic missiles (ICBMs), submarines that launch ballistic missiles (SSBNs), and long-range bombers. Each component of the triad plays a particular role that complements the other two. Bombers provide flexibility, and by changing the tempo of their operations, the United States can signal intent to an adversary. ICBMs provide the most rapid response, and their dispersed underground silos present several hundred targets that an adversary would need to destroy in order to disable the United States’ nuclear forces. The ability of SSBNs to remain on alert while submerged and undetectable for long periods makes them the most difficult of the three components to destroy and ensures that the United States can retaliate against a nuclear attack. That ability to retaliate and assure the destruction of an adversary that launched a nuclear attack helps provide stability during a crisis by deterring adversaries from using nuclear weapons.

The most recent arms control treaty between the United States and Russia, New START, limits strategic forces to 700 deployed (800 total) delivery systems and 1,550 deployed warheads. To comply with those limits when they take effect in 2018, the United States plans to maintain a nuclear force consisting of the following: 12 deployed (14 total) Ohio class SSBNs that together carry up to 1,090 warheads on 240 missiles; 400 deployed (454 total) Minuteman III ICBMs, each carrying a single warhead; and 60 deployed (66 total) B-52H and B-2A bombers, each of which counts as a single warhead under New START rules.

Almost all components of the United States’ nuclear forces are scheduled to be modernized (refurbished or replaced by new systems) over the next 20 years. Current plans call for developing and purchasing 12 new SSBNs, 642 new ICBMs (of which up to 450 would be fielded in existing silos after they were refurbished; the remainder would be spares and test stock), and 80 to 100 B-21 bombers, the next-generation long-range strategic bombers currently under development. Through the mid-2030s, modernization is expected to roughly double annual spending on nuclear forces (currently about $20 billion).

This option would reduce the cost of modernization by retiring some existing delivery systems early and by purchasing fewer of the new systems, but it would allow the United States to retain the strategic benefits provided by the complementary roles of the legs of the triad. The Congressional Budget Office examined two alternative approaches to reducing the size of the triad: The first would keep U.S. forces at the New START limit of 1,550 warheads, and the second would make deeper cuts and reduce the number of deployed warheads to 1,000. Neither alternative would change the size or composition of the planned bomber fleet because the number of bombers is determined largely by their conventional (that is, non-nuclear) mission.

Smaller Triad With 1,550 Warheads

The first alternative would reduce forces to 10 SSBNs and 300 ICBMs and would load more warheads on SSBNs or ICBMs. Under this alternative, the Navy would retire 4 Ohio class SSBNs at a rate of one per year starting in 2018; delay by one year the purchases of new SSBNs included in its current shipbuilding plan, starting with the second submarine, which is slated to be procured in 2024; and cancel orders for the last 2 SSBNs scheduled to be purchased under the current plan. In addition, the Department of Defense (DoD) would retire 150 ICBMs—50 each year for three years starting in 2018—and procure 482 new ICBMs instead of the 640 that are in the current plan. Over the next decade, this alternative would reduce the need for discretionary budget authority by $12 billion, CBO estimates. Outlays would decrease by $9 billion over that period. However, the majority of savings from this alternative would occur after the 10-year period, when DoD would purchase fewer new systems and operate fewer systems overall than it would under the current plan.

An argument in favor of this approach is that it would reduce the cost of nuclear modernization without sacrificing the complementary roles of the triad or reducing the size of the nuclear forces significantly below those permitted under New START. In addition, scaling back plans now may reduce the chances of problematic programs being canceled later and thus may prevent development funding for such programs from being wasted.

An argument against this alternative is that it would reduce the capabilities of the nuclear forces. In particular, with fewer boats the Navy may not be able to meet the current requirements for the number of SSBNs on patrol even though the number of warheads deployed with the submarine fleet could remain the same as under the current plan. In addition, cutting the number of ICBMs that were deployed by one-third would present fewer targets to an adversary, thereby increasing the likelihood that such an adversary could disable that leg of the United States’ nuclear triad.

Smaller Triad With 1,000 Weapons

The second alternative under this option would make deeper cuts to forces but still retain a triad structure. Under this alternative, the Navy would field 8 SSBNs and the Air Force would deploy 150 ICBMs. That force level would be reached by retiring existing systems early, starting in 2018, and by purchasing fewer replacement systems. Over the coming decade, those steps would reduce the need for discretionary budget authority by an estimated $17 billion. Outlays would decrease by $13 billion. As with the first alternative, the majority of savings would occur after 10 years, when DoD would purchase and operate fewer modernized systems.

An argument in favor of this alternative is that a force with 1,000 warheads would comport with the Nuclear Weapons Employment Strategy of the United States, released in 2013, which states that the United States could maintain a “strong and credible” strategic nuclear deterrent with about one-third fewer weapons deployed than allowed under New START. Such a reduction would continue the trend started by earlier treaties, which have made the United States’ current nuclear arsenal about 85 percent smaller than it was at its peak during the Cold War. Some analysts argue that further reduction would strengthen efforts at preventing nuclear proliferation by continuing the United States’ compliance with the Nuclear Non-Proliferation Treaty, in which countries with nuclear weapons agreed to work toward reductions in and the eventual elimination of such weapons and, in exchange, countries without nuclear weapons agreed not to develop or acquire them.

An argument against this alternative is that unless a new arms control agreement was reached—which may not be possible in the current international atmosphere—the United States’ decision to reduce its stockpile to 1,000 warheads would be unilateral and could be politically untenable domestically. Internationally, those allies that do not have their own nuclear weapons and rely on U.S. nuclear forces to deter attacks would probably oppose such cuts. If they determined that a reduction to 1,000 warheads signaled that the United States was less committed to protecting them than it has been in the past, they may choose to pursue their own nuclear weapons programs, which could provoke regional arms races. Furthermore, this approach would reduce the capabilities of U.S. nuclear forces even more than would the first alternative. The possibility of the Navy’s encountering difficulties in meeting SSBN patrol requirements under this alternative would therefore be greater than under the first, and the smaller ICBM force would present even fewer targets to an adversary.