Michael KreponTopping-off National Missile Defenses for Tac Nuke Reductions?

Lyrics of the week:

[way too politically incorrect for this space]

– “Under My Thumb” by The Rolling Stones, retort by Shemekia Copeland

Decades have passed since the Anti-Ballistic Missile Treaty was negotiated (1972), the Soviet Union dissolved (1991), George W. Bush announced U.S. withdrawal from the treaty (2001), North Korea flight tested a missile capable of spanning the Pacific Ocean (2017), and China began to deploy intercontinental-range missiles in significant number (2021).

Throughout, the fundamentals of what missile defenses can and cannot do haven’t appreciably changed. Effective national missile defenses for a country as big as the United States remains an impossible task against a powerful adversary determined to get through — no matter how much money the Congress appropriates for this purpose. Theater missile defenses deployed far from U.S. shores are a better investment, as they have greater military and political utility.

Not being able to succeed against worst cases doesn’t mean it’s worthless to try against lesser cases. Limited national missile defenses could have some chance of success against some horrific contingencies. To remain completely defenseless is morally indefensible in the event of, say, a profoundly unwise decision by a desperate outlier to launch ocean-spanning missiles. The odds of this happening are low, since outliers prefer to live to a ripe old age and to remain in power. Because of these odds, national missile defense deployments need not be overbuilt. This, in turn, offers the additional benefit that Moscow and Beijing do not need to overreact to a modest U.S. insurance policy.

Upgrades of theater missile defenses show more promise than upgrades of national missile defenses. These upgrades are valuable because they demonstrate Washington’s commitment to help protect friends and allies. They also backstop U.S. nonproliferation policies. All of the countries most concerned about North Korean and Iranian missile and nuclear programs rely on U.S. support. If they perceive that support to be flagging, some of these countries might be more inclined to possess their own nuclear weapons.

Regrettably, upgrades of national missile defenses are also necessary because what was hurriedly deployed after Bush quit the ABM Treaty doesn’t work well, if at all, even against unsophisticated missile threats. Quantitative and qualitative upgrades need close scrutiny, however. The number of interceptors matter because building out national missile defense deployments will have the expected result: Russia and China will deploy more nuclear warheads atop missiles to defeat more U.S. national missile defenses.

Effective national missile defenses against a peer or near-peer competitor have always been beyond reach, beginning with the problem of radar blackout due to nuclear detonations. National missile defenses that cannot cope with “old fashioned” ballistic missiles and penetration aids face additional challenges with the advent of stealthy, long-range cruise missiles. Next up are “hypervelocity/glide vehicles.”

During the Reagan administration, Paul Nitze argued without effective rebuttal that an added increment of national missile defense wasn’t worth the expense unless it was cost-effective at the margin. In other words, if offensive upgrades are easier, more effective, and less costly than added increments of national missile defense, it is unwise to spend money building out national defenses.

Nitze was right then, and he’s right now. The best defense against a peer competitor is a strong offense. The best defense against outliers like North Korea or Iran is a strong offense, supplemented by increasingly capable theater missile defenses and minimal national missile defenses.

Topping-off national missile defenses that are bound to fail against major rivals could serve three useful purposes. First, this would remove one (but only one) of the Kremlin’s concerns over disadvantage, opening up possibilities for agreements that reduce nuclear danger. Second, topping-off would remove one (but only one) of the reasons Beijing has to increase further its deployments of ocean-spanning missiles. Third, limitations on national missile defenses would allow the Pentagon to spend money on programs with greater military and political utility. Every conventional military upgrade the Pentagon seeks is more cost-effective at the margin than build-outs of national ballistic missile defenses.

Nonetheless, some in the United States continue to insist on spending large sums for “layered” national missile defenses, while some in Russia continue to express concern about U.S. missile defense upgrades. This conjunction opens up the possibility for deal making.

In the past, U.S. Presidents have traded top-offs on national missile defenses for a freeze and then deep reductions in strategic offensive arms. Can the Biden administration trade the same horse a third time for deeper reductions?

There are many reasons why a third trade seems hard to achieve. Previous trades were rooted in a treaty that no longer exists. Besides, Washington and Moscow are both justifiably wary of Beijing’s strategic modernization plans. Draw-downs are harder when a major power is ramping up. There are probably several reasons for Beijing’s build up. One might be to strengthen its hand in the event of trilateral talks.

Previous deals linking offenses and defenses were formal and verifiable. If Moscow insists on treaties and formality, new offensive-defensive deals won’t happen in the years ahead. Treaty ratification requires super-majorities in the U.S. Senate, without which treaty withdrawals happen and new treaties do not enter into force. The promise that treaties once provided for long-term stability and predictability in strategic offensive forces has faded.

This isn’t the end of the story, however. Linkages between missile defenses and strategic offenses still exist. They are no less real when they are informal. Major powers will continue to seek assurance, stability, and predictability. If formalized offensive-defensive tradeoffs are not possible, they might still be consummated by means of parallel restraints. Restraints can take the form of executive, tacit, or informal agreements. These agreements might not be as good as treaties, but they are better than arms buildups and arms racing.

Continued U.S. restraint on national missile defenses could reinforce limits on strategic offensive forces set by the “New” Strategic Arms Reduction Treaty extended earlier this year by Presidents Joe Biden and Vladimir Putin. Marginal mutual reductions from these limits might be conceivable if limitations on national missile defenses remain in place — but, again, the Chinese build up doesn’t help matters.

If classic trades involving national missile defenses and strategic offensive arms are unlikely, are other trades conceivable? An imaginative approach would be required. What does Russia possess in wretched excess that has as little military utility as national missile defenses, but that nonetheless worries U.S. deterrence strategists? In professional sports, teams trade players with overpriced, long-term contracts. Can nuclear-armed rivals agree to parallel constraints on legacy programs with significant sunk costs that do not provide sound return on continued over-investment?

Parallel constraints topping-off national missile defenses alongside verifiable limits, reductions, and dismantlement of Russian tactical nuclear warheads would be highly irregular. And yet, parallel restraints along these lines have a strange, intriguing symmetry. U.S. deterrence strategists are as bent out of shape about Russian tac nukes as Russian deterrence strategists are fixated on U.S. missile defenses. The military utility of U.S. national missile defenses and Russian tac nukes does not extend beyond very limited contingencies.

The U.S. Army concluded during George H.W. Bush’s extraordinary presidency that tactical nuclear weapons weren’t useful for fighting ground wars. Mushroom clouds get in the way. They impair mobility and are not good for seizing and holding ground. Their use invites uncontrolled escalation, and they are a security nightmare to keep safely near the forward edge of battle. It appears that Beijing has reached the same conclusions.

The Russian Army ought to be smart enough to figure out what the U.S. Army has learned and what the Chinese Army appears to practice. Then again, Russian deterrence strategists might continue to see value in weapons that worry their U.S. counterparts so much. The same thought, as well as other rationales, has sustained U.S. national missile defense advocates in the face of brutally difficult technological and operational challenges.

Informal or tacit agreements topping-off U.S. national missile defense deployments alongside verifiable reductions in Russian tactical nuclear weapons would be very hard to accomplish. To begin with, limitations on U.S. national missile defenses can be verified easily; not so for reductions in Russian tactical nuclear weapons. These might usefully be explored in the context of broader, mutual transparency measures for warhead dismantlement, but this would take time.

In the meantime, those in the United States who strenuously insist on limitations and reductions in Russian tactical nuclear weapons are determined to build out national missile defenses. These goals mesh only if one’s definition of success is the failure of arms control — in which case Russian tac nukes would remain unconstrained and U.S. national missile defenses would remain ineffective.

The Biden administration has yet to share with us its definition of success in the strategic stability talks. We do know, however, that success requires making sound choices. Biden’s decisions on national and theater missile defenses will be made on national security interest-based grounds. The Kremlin doesn’t get a veto. Nor does Washington have a veto on Moscow’s requirements for tactical nuclear weapons. There are sound reasons for parallel restraint, but these decisions won’t be sealed by trade or by treaty; they’ll reflect national security calculations.

Parallel restraint is probably the best we can expect in the near term. Restraint is inherently impermanent, but treaties are also impermanent — even those intended to have indefinite duration like the ABM Treaty and the Intermediate Nuclear Forces Treaty.

Whether restraints are informal or treaty-based, their longevity will depend on how much national leaders value freedom of action and whether there are perceived advantages in ditching restraint. The likelihood of parallel restraint regarding national missile defenses and tac nukes could increase if these concerns rank high enough in Moscow and Washington’s respective priorities in the strategic stability talks.


  1. Researcher from Seoul (History)

    Hi, Dr. Krepon, I’m a researcher in Seoul, and have been a huge fan of your posts. Your idea is truly interesting, and makes me say something on that. Thank you very much, and sorry for replying anonymously due to my affiliation.

    As far as I know, US concerns about Russia’s tactical nuclear weapons seem to be mostly about the so-called escalate to de-escalate doctrine in Europe. In other words, if Russia were to give up its tactical nuclear weapons, the biggest beneficiaries would be the US’s European allies, but many would think the potential harm of US abandonment of NMDs would be voters living on the continental US. Could Capitol Hill or American voters accept this structure?

    • Michael Krepon (History)

      Dear Researcher from Seoul:
      Thank you for your kind words.
      Yes, U.S. allies in Europe would be the prime beneficiaries of Russian reductions of tac nukes. This step is possible, in my view, if Moscow wishes to improve relations with NATO countries that it has alienated. It is also possible because the likelihood that Russian forces will wage a ground campaign to seize and hold territory with tactical nuclear weapons is less than low. The ‘escalate to de-escalate’ hypothesis is a fever dream. It’s what we would expect from deterrence strategists with firmly held beliefs that nuclear weapons have great war-fighting utility. Instead, tactical nuclear weapons or any nuclear weapons do not help ground forces to wage a military campaign. The Russian threat to its neighbors is serious, but it now takes the form of hybrid warfare.
      I do not anticipate that the Biden administration will abandon national missile defenses. As I’ve argued, I continue to believe that a limited insurance policy is needed. So, unlike the past, I don’t think the executive and legislative branches will accept zero deployments. I also believe the U.S. public will accept a limited insurance policy, and will oppose an expensive, “layered” defense against ballistic missile attacks on the homeland. So, I expect upgrades of current interceptors, which were hurriedly deployed and which may not work at all, while limiting their number.
      Best wishes,

  2. Michael Krepon (History)

    Update and correction: China appears to be preparing a third ICBM base in Inner Mongolia. This means that its growth rate equals that of the Soviet Union in the run up to SALT. Is there a fourth base out there, too?