Meeting the Challenge of Deterring Two Nuclear Peers

This June 4, 2021, satellite image provided by Planet Labs Inc. that has been annotated by experts at the James Martin Center for Nonproliferation Studies at Middlebury Institute of International Studies shows what analysts believe is a field of intercontinental ballistic missile silos near Yumen, China. The U.S. military is warning about what analysts have described as a major expansion of China's nuclear missile silo fields, at a time of heightened tension between the U.S. and China. (Planet Labs Inc., James Martin Center for Nonproliferation Studies at Middlebury Institute of International Studies via AP)

In the past, U.S. nuclear forces were focused on deterring Russia; China was a lessor included case in the sense that if the U.S. had the capabilities needed to deter the Soviet Union, it surely could also deter China. The emergence of China toward nuclear peer status, seen as a prospect for the mid-2030s, changes that calculation. Quoting from the Biden NPR:

By the 2030s the U.S. will, for the first time in its history, face two major nuclear powers as strategic competitors and potential adversaries. This will create new stresses on stability and new challenges for deterrence, assurance, arms control, and risk reduction.[iii]

Deterring a hostile Russia and China, possibly at the same time, has been a fixture of U.S. policy for decades. During the Cold War, even in light of a major nuclear exchange with Russia, sufficient survivable warheads were maintained to deter any incentive by China to “pile on.”  This was during a time when both Russia and the United States maintained many thousands of strategic warheads, while China possessed just a few tens of ICBMs. There was both quantity and flexibility then in U.S. forces to deter both. Today, with deployed strategic, accountable warheads under New START capped at 1550, estimates are that China will field one thousand additional ICBM warheads by 2035.[iv]  Moreover, the intensive, ongoing U.S. program to modernize each leg of the aging Triad leaves little excess capacity to respond with new nuclear program starts in the near term. What to do?

Most simply put, U.S. deterrence strategy for decades has been to hold at risk those assets valued most highly by adversary national leaders. This includes the ability to prosecute conventional and nuclear warfare.[v]  Some, however, incorrectly characterize this strategy as a choice between holding forces at risk, most specifically nuclear forces, or threatening cities and population centers with the express purpose of killing innocent civilians, which they unfortunately label as countervalue targeting.[vi]^,[vii]  If the United States altered its current deterrence strategy to intentionally target population and not forces, they argue, it could avoid the need for a costly buildup in response to China’s ICBM buildup.[viii]  That argument and its ramifications have been thoroughly countered in a recent piece which, in line with past rigorous studies, calls into question whether authoritarian regimes such as in Moscow and Beijing are adequately deterred by threats to their populace.[ix]  In these regimes, human lives appear to be viewed as tools of the state and therefore expendable in service to the state, rather than as in democracies where the state seeks to serve its citizens and ultimately is answerable to them.[x]

To be clear, the United States adheres to the international Law of Armed Conflict (LOAC) and does not intentionally target cities or population.[xi]  U.S. policy is to minimize civilian casualties in wartime operations. That said, striking targets that are co-located with civilian centers or objects may be consistent with the LOAC if their military significance is high—even though destroying such targets could result in a number of unintended casualties. In some cases, however, such installations will not be targeted because avoiding the prospect of inflicting excessive unintended collateral damage must take precedence.[xii]

U.S. deterrence strategy, very importantly, depends on the specific adversary to be deterred and is neither solely counterforce nor countervalue but involves a mix of targets that are all tied to the adversary’s value structure and its ability to pursue warfare. The potential cost incurred in their destruction is intended to ensure that no rational adversary would ever contemplate a nuclear attack of any scale against the United States or its allies.

U.S. nuclear forces include a robust capability to hold adversary nuclear forces at risk. Over the years, this has been a topic of debate. But to be clear, the main area of contention is not U.S. counter nuclear force capabilities but U.S. prompt counter nuclear force capabilities represented largely by its ICBM force.  Indeed, most warheads in the U.S. nuclear arsenal, and even some conventional weapons systems today, have sufficiently high accuracy and explosive power to hold at risk many of the hardest military targets fielded by adversaries including nuclear forces. Only ICBMs, however, can deliver such warheads to targets within 30 to 60 minutes of a President’s decision to execute such a strike. A prompt counterforce component of the U.S. nuclear triad is important for several reasons:

This last point deserves clarification. During the Cold War, accurate, large throw-weight, highly-MIRVed, silo-based Soviet SS-18 ICBMs represented a significant disparity in prompt counterforce capability compared with the U.S. ICBM force of lower throw-weight, less-highly-MIRVed Minuteman IIs and IIIs. Fewer than 100 out of a total 300 deployed SS-18s could target each Minuteman silo with two warheads, eliminating most U.S. ICBMs. In the Carter-Reagan nuclear modernization program, this disparity was redressed by fielding two highly accurate ballistic missile systems: the 10-warhead Peacekeeper ICBM and the 8-12 warhead Trident D-5 SLBM (also with prompt delivery capability if not as responsive).

This was controversial: Wasn’t the U.S. making matters worse by incentivizing the Soviets to put their ICBMs on “hair trigger” alert, both decreasing crisis stability and increasing the chance of an inadvertent launch based on false warning? What actually happened was that once their fixed ICBMs were being held at comparable risk, the Soviets adjusted their force by trending to lower throw-weight, less highly-MIRVed, and more survivable mobile ICBMs. At the same time, they demonstrated an increased propensity to limit the silo-based SS-18s in arm control agreements. By taking on a near-term risk of potentially increased crisis instability, the U.S. shaped the arms competition towards a longer-term, more stable evolution in forces. Later on, when New START was concluded, the Obama administration downloaded the Minuteman IIIs to single warhead thus strengthening crisis stability by making them a much less desirable target to attack.

One complexity regarding force sufficiency and deterrence involves the potential for various levels of Sino-Russia security coordination. If the Russian and Chinese nuclear (and conventional) threats were independent and uncorrelated, then the two nuclear peer deterrence problem would be more manageable. If the U.S. and Russia were to agree in some form, once New START expires in 2026, to continue limits on warheads and delivery systems, there would be little need to augment U.S. strategic forces in regard to Russia. If China stopped once it achieved peer status, some adjustment to targeting priorities may be warranted but not likely a pressing need for U.S. force augmentation. If the threats are uncorrelated, planned U.S. strategic forces are likely sufficient to deter.[xiii]

If China and Russia coordinate in their planning and force posture, then this calculus changes and will depend on the details. Coordination could range from minimal consultations or assistance to, perhaps less likely, a full-fledged alliance between the two countries with integrated forces and force planning. For example, if U.S. forces were engaged in a NATO-Russia conventional conflict, with accompanying nuclear overtones, China, even with minimum coordination with Russia, could exploit this opportunity “on the fly” to pursue its threat to take over Taiwan by force. A proactive (and, notwithstanding, expensive) strategy would be to posture sufficient conventional forces, combined with forces provided by allies, to deter this second conflict while fighting the first, and to retain sufficient nuclear forces to deter one or both conflicts from going nuclear. In light of recent developments, including in the nuclear arena, we must assume some degree of Sino-Russian cooperation in regional conflict.[xiv]

As stated earlier, U.S. policy is to hold at risk critical assets and installations most valued by enemy leaders. An adversary’s nuclear forces might well fall into that category. In the case of China’s ongoing ICBM ramp up, the U.S. must decide whether and how to hold such forces at risk. One alternative is a force augmentation involving additional U.S. ICBM warheads.

Whether to hold the entire Chinese ICBM force at risk, some portion of it, or none of it is an open question. Indeed, U.S. policy specifies a role for counterforce targeting “only to the extent practicable or feasible.”  For example, Russia’s 1990s initial deployments of mobile ICBMs made these forces more difficult to target. The policy seemed then to suggest: “OK to continue to try to hold mobile ICBMs at risk, but plan to do so with available forces and don’t expect a ramp up that would exceed existing limits in order to meet a more demanding requirement.”  U.S. strategic force augmentation, depending on whether any agreed limits on forces are put in place after New Start expires, may require adjustment to this policy.

There is a benefit to the U.S. having a capability to hold some portion of China’s silo-based ICBMs at prompt risk. And not just for damage limitation. The Chinese should come to understand, as the Russians eventually did, that these systems are not being given a “free ride,” thus providing some disincentive to the ongoing ramp-up. [xv]  In light of possible Sino-Russian coordination, this would require some augmentation of U.S. ICBMs (and potentially SLBMs). Depending on assessment of the likelihood of various levels of cooperation, this shortfall could be redressed with a smaller or larger force augmentation. Effective U.S. ballistic missile defenses could lower augmentation needs as could, potentially, additional forward deployments of existing, and potentially new types of U.S. non-strategic nuclear forces.

In the near term, U.S. forces could be augmented by uploading reserve warheads to existing delivery systems. Re-MIRVing Minuteman III and, at some cost in responsiveness, uploading warheads to fill currently-unoccupied slots on the Trident D-5 SLBM could add several hundred additional warheads to the deployed force.[xvi]  Ensuring that sufficient reserve warheads are available (and not placed in the dismantlement queue!), and timely provision of tritium and limited-life components (e.g., gas bottles, neutron generators) to activate reserve warheads is essential.  Once activated, timelines for weapons upload will vary depending on the delivery system—days to weeks for bombers, weeks to months for the subs, and one to three years for ICBMs. To be sure, uploading does add some operational inefficiencies. Still, this is not an insignificant force augmentation capability by any measure.

How many warheads might need to be uploaded? China may add about one thousand ICBM warheads (350 silos) by 2035 with about half fielded by 2030.[xvii]  If upload is primarily to hold at risk some portion of China’s silo-based ICBMs, options could include—700 additional warheads (2 per silo), 350 additional warheads (one per silo), or quite possibly fewer depending on willingness to accept risk.  Two on one targeting will be seen as, and indeed is, excessive. Given this admittedly rough estimate and assuming that Russia remains at roughly current levels, in the nearer term at least no more than a few hundred additional ICBM warheads could meet “two peer” deterrence needs.

One study argues to upload reserve warheads starting in 2026 when New START expires.[xviii]  This may be premature assuming a hedge upload capability that can be fully executed in one to three years, well before China’s new ICBMs become fully operational in 2035. If this estimate holds, there is more time to work the “two peer” problem while pressing to eliminate any force upload capability shortfalls.  And what if, after New START expires, Russia presses to extend limits in some form simply to constrain any U.S. upload so that China might catch up? Would the U.S. reject such a proposal from Russia? Pressing for an earlier than needed upload, possibly via a unilateral decision not to seek to extend arms limits, would be contentious and has potential to upset the so far bipartisan consensus on modernization. On the other hand, being skeptical of intelligence assessments is prudent policy; we must consider that China could accelerate its buildup. Uploading sooner hedges that risk.

If one is optimistic regarding the 2035 estimate, prudent and timely U.S. force augmentation would begin in the 2030 timeframe. This would provide time both to build a political consensus for augmentation without jeopardizing the ongoing modernization program, and to fix any force upload shortfalls. It would also provide time for other strategies (e.g., diplomacy, arms control, U.S.-China dialog on strategic stability) that, while perhaps unlikely to succeed in the current security environment could, if they did, conceivably mitigate if not alleviate upload needs.

The most likely path to peer nuclear conflict involves escalation from an ongoing regional conventional conflict. Increased forward-deployment of U.S. conventional forces could help to deter such conflict in the first place by the ability to bring force to bear more quickly and reduce reliance on vulnerable reinforcement routes. The goal is to prevent faits accomplis. In recent years, progress has been made in NATO Europe, but more could be done there and in Asia. In addition, conventional deterrence could be strengthened by ensuring that weapons and command and control assets are sufficiently hardened to moderately severe nuclear environments, and that the U.S. regional commands, supported by Strategic Command, adapt their planning to fight the war once nuclear weapons are introduced to the conventional battlefield. Additional deployment of new or existing types of U.S. non-strategic nuclear forces, to include a modern nuclear, land-attack sea-launched cruise missile (SLCM-N), would bolster deterrence and help reduce the need for ICBM warhead augmentation.

The Biden team, if it is not already doing so, should, with urgency over coming months, establish a DoD-led process to review the Russian and Chinese nuclear programs, their potential for acceleration, the implications of Sino-Russia condominium in the nuclear arena and the status of U.S. force upload capabilities, and develop a set of response options for Presidential decision.  At minimum, a decision is warranted to ensure a viable, executable option to field a few hundred additional ICBM warheads to meet emerging deterrence needs in the 2030 timeframe.

I would like to acknowledge very useful discussions with Frank Miller, Keith Payne, Brad Roberts, and Rob Soofer in preparing this paper.  Recommendations and conclusions are my own.

John R. Harvey, Ph.D., served in senior posts in the Departments of Energy and Defense overseeing U.S. nuclear weapons policies and programs including, from 2009-13, as Principal Deputy Assistant Secretary of Defense for Nuclear, Chemical, and Biological Defense Programs.

[i]  China’s Emergence as a Second Nuclear Peer—Implications for U.S. Deterrence Strategy, A Report of a Study Group Convened by the Center for Global Security Research at Lawrence Livermore National Laboratory, 2023.

[ii]  Karl Lieber and Darrell Press, “US Strategy and Force Posture for an Era of Nuclear Tripolarity,” Issue Brief, Atlantic Council, April 2023.

[iii]  2022 Nuclear Posture Review, unclassified version issued by the Biden administration on 27 October 2022.

[iv]  Military and Security Developments Involving the People’s Republic of China, 2022, Annual Report to Congress, Office of the Secretary of Defense, 2022.

[v]  So-called counterforce targets include conventional and nuclear forces whether stationary or on the move, associated infrastructure, industry that supports these forces, and national political and military control. Nuclear counterforce targets include ICBM silos, mobile ICBMs, submarine bases, strategic bomber bases, elements of the nuclear command and control system, ballistic missiles and bombers on route to targets and air and missile defenses.

[vi]  See Lieber and Press, op cit.

[vii]  “Countervalue” in the context of nuclear targeting is an unfortunate term because it is imprecise.  It includes cities and population but is more than that.  It can also include certain high-value installations, industry or assets that do not directly support an adversary’s warfighting potential.  A more appropriate term for use by the analysts cited would be “counter-population” targeting.

[viii]  Lieber and Press, op cit.

[ix]  Keith B. Payne, John R. Harvey, Franklin C. Miller, Robert Soofer, The Rejection of Intentional Population Targeting for “Tripolar” Deterrence, National Institute for Public Policy Information Series #563, September 2023.

[x]  Ibid.

[xi]  Office of General Counsel, Department of Defense, Law of War Manual, June 2015 (updated July 2023).

[xii]  All targets in U.S. war plans are vetted for military necessity, as well as the criteria of proportionality and distinction which address potential civilian collateral damage.  Proportionality obliges states to “to refrain from attacks in which the expected harm incidental to such attacks would be excessive in relation to the concrete and direct military advantage anticipated to be gained and to take feasible precautions in planning and conducting attacks to reduce the risk of harm to civilians . . . .”.  Distinction, sometimes called discrimination, “obliges parties to a conflict to distinguish principally between the armed forces and the civilian population, and between unprotected and protected objects.”  Ibid.

[xiii]  Adjustments in U.S. non-strategic nuclear forces may still be warranted if needed, among other things, to assure allies of our commitments to come to their defense in light of extensive Russian deployments of these systems.

[xiv]  In 8 March 2023 testimony before the House Armed Services Subcommittee on Strategic Forces, John Plumb, Assistant Secretary of Defense for Space Policy, called attention to Russia’s provision of highly-enriched uranium for use in China’s breeder reactors.  According to Plumb “. . . there's no getting around the fact that breeder reactors are plutonium, and plutonium is for weapons.”  One might speculate that this could be in exchange for support (e.g., arms transfers) in the ongoing conflict with Ukraine.  Russia and China jointly issued a statement in February 2023 highlighting security cooperation in which both leaders noted “Friendship between the two States has no limits.”

[xv]  To be clear, to achieve this benefit does not require holding the entire Chinese ICBM force at prompt risk.

[xvi]  Uploading additional cruise missiles to B-52 bombers—they can carry up to twenty but are typically deployed with fewer—would add significantly to that total.

[xvii]  Military and Security Developments Involving the People’s Republic of China, 2022, op cit.

[xviii]  See China’s Emergence as a Second Nuclear Peer, op cit.