The Potential Costs of Expanding U.S. Strategic Nuclear Forces If the New START Treaty Expires

The New Strategic Arms Reduction Treaty (New START) between the United States and Russia will expire in February 2021 unless both parties agree to an extension, which could last for up to five years. That treaty places limits on the number of deployed strategic nuclear warheads (1,550) and delivery systems (800 missile launchers and bombers, 700 of which may be deployed at any given time) that each country may field.

How and when the United States or Russia would respond to the expiration of New START is unclear. To help policymakers understand the budgetary implications of one potential course of action the United States could take, the Congressional Budget Office was asked to examine the potential costs that the Department of Defense (DoD) might incur if the United States chose to increase its strategic nuclear forces to levels that are roughly consistent with the limits under three earlier arms control treaties.

What Could Happen If New START Expired?

If the New START treaty was allowed to expire, the size of the nuclear arsenals of the United States and Russia would be without limits for the first time in decades. The transparency and confidence-building procedures included in New START and previous treaties would cease, in which case both parties would lose the means to have direct knowledge of their adversary’s capabilities. In the absence of on-site inspections, data exchanges, and limits on the encryption of flight text data, uncertainty about each other’s forces would grow over time.

Many responses to the end of strategic nuclear arms control would be possible, including some that would not affect the size of strategic nuclear forces. For example, uncertainty about the other party’s forces might lead the United States to expand its intelligence capabilities or to hedge against uncertainty about the other party’s intentions by expanding missile defenses. Conversely, the United States might choose to emphasize conventional deterrence by expanding its conventional missile forces or to increase its capabilities for regional conflict by expanding nonstrategic nuclear forces.

In terms of strategic nuclear forces, many different responses also are possible. Each party might opt to make no changes to its current plans for nuclear forces for many years. Or one party might choose to expand its forces, either to seek an advantage or because, without the ability to inspect the other’s forces, it was concerned that the other is building up its arsenal and wants to hedge against that uncertainty. Or both parties might choose to expand their forces, perhaps significantly. The lack of constraints on ballistic missile defenses could further complicate that dynamic. (The United States withdrew from the ABM Treaty, which limited the number and locations of Russian and U.S. defenses against long-range missiles, in 2002.)

How Did CBO Analyze the Issue?

CBO was asked to estimate the costs of increasing deployed U.S. strategic nuclear forces to the levels specified in three previous arms control treaties: the Moscow Treaty (1,700 to 2,200 warheads), the START II treaty (3,000 to 3,500 warheads), and the START I treaty (6,000 warheads). Although each treaty had a different protocol for counting warheads, for this analysis CBO used the rules for the Moscow Treaty because they most closely reflect the number of nuclear weapons actually deployed.

The United States could field a wide variety of force structures, each with very different costs, to reach those levels. To illustrate both ends of the distribution of potential forces and their associated costs, CBO examined two approaches for expanding forces at each warhead level.

• A lower-cost and less flexible approach would increase the number of warheads allocated to each missile and bomber to, or near to, its maximum (an approach known as uploading) and minimize the number of additional delivery systems purchased, if any.
• A more flexible and higher-cost approach would purchase enough delivery systems to reach the desired total numbers of warheads while maintaining (as nearly as possible) the current number of warheads allocated to each missile and bomber.

DoD also could choose to field a force that lies between those two approaches. To estimate costs, CBO used methods from its previous work on nuclear forces.

What Did CBO Find?

If the New START treaty expired, the United States could choose to make no changes to its current plans for nuclear forces, in which case it would incur no additional costs. If the United States chose to increase its forces in response to the expiration of the treaty, modest expansions could be relatively inexpensive and could be done quickly. Larger expansions could be quite costly, however, and could take several decades to accomplish. Accelerating production of additional forces would probably have only a small effect on that timeline and could increase costs.

• Expanding forces to the Moscow Treaty limits would have no effect on DoD’s costs, because current and planned next-generation forces are both already at those limits.
• Expanding forces to START II limits could be relatively inexpensive if DoD used a lower-cost approach that involved uploading warheads only: about $100 million in onetime costs for DoD (with no additional ongoing operation and sustainment costs) for both current and next-generation forces, CBO estimates. If DoD used a more flexible approach that involved purchasing enough delivery systems to maintain current warhead loading levels, that expansion would be much more expensive, eventually totaling $114 billion to $172 billion in acquisition costs over several decades and $3 billion to $8 billion in additional annual costs after the expanded forces were in place. The additional costs of expanding to START II limits under the more flexible approach would lead to total production costs roughly 50 percent higher than currently planned (see Figure 1).
• Expanding forces to START I limits would require even more new delivery systems and warheads. Under a lower-cost approach that minimized the number of additional delivery systems, DoD would incur onetime costs of $88 billion to $149 billion over several decades to buy additional delivery vehicles and $4 billion to $10 billion in additional operation and sustainment costs each year, in CBO’s estimation. Under a more flexible approach that maintained as much as possible the current number of warheads loaded on missiles and allocated to bombers by having DoD purchase enough delivery systems, CBO estimates that DoD would incur onetime costs eventually totaling $410 billion to $439 billion to purchase additional systems as well as additional annual operation and sustainment costs (beyond those for planned forces) of $24 billion to $28 billion after the expanded forces were in place. The additional costs of expanding to START I limits under the more flexible approach would lead to production costs nearly three times those currently planned (see Figure 1).

For comparison, the costs to produce the currently planned quantities of next-generation delivery systems is about $240 billion, CBO estimates, not including development costs.

What Costs Were Excluded From This Analysis?

The figures cited in this report do not include the Department of Energy’s (DOE’s) costs of producing or maintaining additional warheads. Most information about the nuclear stockpile is classified, so it is difficult to determine whether and how many additional warheads would be needed and thus what additional funding would be required. Those costs could be considerable, though, for all but modest increases in forces.

CBO’s estimates also exclude DoD’s costs of establishing new operating bases and training facilities (if needed) and DoD’s costs of expanding production capability for delivery systems (if needed because production is accelerated). CBO also excluded the costs of other actions that the United States might take if New START expired without another agreement in place, including expanding U.S. intelligence capabilities, strengthening missile defenses, increasing long-range conventional (that is, nonnuclear) missile forces, or expanding short-range nuclear forces.