After New START: What Next?

Steven Pifer

Assuming the New Strategic Arms Reduction Treaty (New START) is ratified and enters into force, the question will be, “What next?” Speaking in Prague in April 2009, President Barack Obama called for reducing the role and number of nuclear weapons and articulated the goal of a world free of nuclear arms, albeit only when certain conditions are met. He and his Russian counterpart, President Dmitry Medvedev, have agreed to a step-by-step process for reducing nuclear weapons.

The political climate in the United States has changed greatly since the spring of 2009, and Senate Republicans raised a number of concerns about New START during ratification hearings. Those concerns and the new political dynamic following the November 2010 midterm elections would need to be taken into account in any future strategic arms reduction negotiation.

Nevertheless, assuming that the New START Treaty is ratified, something presumably will follow. The next negotiation, however, will be a longer, more complex process than the one that produced New START. The United States and Russia will need to address a number of issues: How much further are they prepared to go in reducing deployed strategic warheads? Will they agree to parallel cuts in New START’s limits on intercontinental ballistic missiles (ICBMs), submarine-launched ballistic missiles (SLBMs), and nuclear-capable heavy bombers?

When signing New START this past April, Obama stated, “[G]oing forward, we hope to pursue discussions with Russia on reducing both our strategic and tactical weapons, including nondeployed weapons.”[1] This opens the possibility that, for the first time, negotiations might cover all U.S. and Russian nuclear warheads. This would entail new challenges for the negotiators.

Other issues are bound to arise. The Russians may raise concerns about long-range conventional weapons, which they fear could threaten their strategic forces. Moscow likely will return to the issue of missile defense. Third-country nuclear forces could come up.

Washington probably will take an incremental approach to reductions in the next round rather than seeking a dramatic cut. First of all, it is unlikely that, between now and the start of new negotiations, the Obama administration will conduct a review leading to a radical shift in nuclear doctrine or nuclear force posture; in April 2010, the administration completed a nuclear posture review, which set out guidance for reducing the role of nuclear weapons while maintaining strategic deterrence and stability at lower levels of nuclear forces. Also, the administration has to weigh what is achievable with Moscow, where many appear unenthusiastic about further reductions, and what could be approved by the Senate.

In light of these considerations, this article proposes that, in a negotiation on a New START follow-on agreement, U.S. negotiators seek a limit on all strategic and nonstrategic nuclear warheads, except for those retired and in the queue for dismantlement, of no more than 2,500 with a sublimit of no more than 1,000 deployed strategic warheads. U.S. officials might propose to keep deployed strategic delivery vehicle and launcher limits at New START levels, but should be ready to consider lower numbers.

An agreement along these lines likely would entail a two-tiered verification system. The sides would have strong confidence in their ability to monitor the limits on deployed strategic systems and detect militarily significant violations of those limits, but weaker confidence as to verifying limits on nonstrategic and nondeployed strategic warheads. This would be preferable to having no limits on and no monitoring of Russian tactical nuclear weapons.

This new agreement would address U.S. and Russian nuclear forces only, although any further cuts almost certainly would have to take place in a multilateral context. The new agreement would not constrain missile defenses, which hopefully will become a subject of U.S.-Russian or NATO-Russian cooperation.

New START and Its Impact

New START limits U.S. and Russian strategic nuclear forces so that seven years after the treaty’s entry into force, each side will not exceed 700 deployed ICBMs, SLBMs, and nuclear-capable heavy bombers; 1,550 warheads on deployed ICBMs and SLBMs and attributed to nuclear-capable heavy bombers; and 800 deployed and nondeployed ICBM and SLBM launchers and deployed and nondeployed nuclear-capable heavy bombers. New START counts the actual number of warheads on deployed ICBMs and SLBMs, but counts each nuclear-capable heavy bomber as just one warhead under the 1,550 limit, regardless of capacity or operational load. (Both sides thus will likely deploy somewhat more than 1,550 warheads.)

New START’s verification measures include data exchanges, unique identifiers, notifications, and on-site inspections in addition to reliance on national technical means of verification. The treaty also provides, as a transparency measure, that the sides exchange telemetry on up to five strategic missile launches per year. (Telemetry is the information a missile broadcasts during a flight test to report on its performance.)

U.S. strategic forces had 1,968 deployed warheads as of December 31, 2009.[2] Although the Russians had fewer deployed ICBMs, SLBMs, and bombers, they deployed an estimated 2,600 strategic warheads at the beginning of 2010.[3] In implementing New START, the U.S. military intends to take full advantage of the limits, deploying 1,550 warheads on 240 Trident D-5 SLBMs, 400 to 420 Minuteman III ICBMs, and 40 to 60 nuclear-capable B-2 and B-52H bombers; the Pentagon will need to decide between 20 ICBMs or bombers to fit within the 700 limit. The Russians have not described their planned residual strategic forces yet; their original 2009 proposal for New START was for a limit of 500 strategic delivery vehicles.

Deployed Strategic Forces

Assuming an incremental approach to nuclear arms reductions, the Obama administration should consider proposing 1,000 as the deployed strategic warhead limit for the New START follow-on treaty. That would mean a significant cut below New START levels, but should be high enough so that third countries would not need to be included. A limit of 1,000 warheads should suffice to allow the United States to maintain a triad of ICBMs, SLBMs, and heavy bombers although it would begin to strain the U.S. ability to do so. For example, were reductions to drive the U.S. Air Force to less than 40 nuclear-capable bombers, it is not clear that a viable bomber leg of the triad could be sustained.

The next agreement should continue to use New START’s “actual load” rule for counting warheads on ICBMs and SLBMs, including conventional warheads on strategic ballistic missiles. The Pentagon has said that any deployment of conventional warheads would be a “niche capability,” suggesting a requirement measured in the tens. Although some analysts, as a matter of principle, oppose any limits in a strategic arms treaty that constrain conventional weapons, in practical terms, a few tens of conventional warheads would not cut deeply into a treaty allowance of 1,000 strategic warheads.

New START attributes each nuclear-capable bomber with one warhead under the 1,550 warhead limit, even though some can carry as many as 16 to 20 air-launched cruise missiles. Negotiators justified that approach by long bomber flight times (eight to 10 hours); aircraft do not pose the same threat of surprise attack as ICBMs or SLBMs, which have flight times of 15 to 30 minutes. In the next negotiation, the sides should consider increasing the number, perhaps to three to four warheads per aircraft, which would maintain the logic of “discounting” while reducing the amount. An alternate approach, which would entail no discount, would count all nuclear weapons stored at heavy bomber bases under the deployed strategic warhead limit. This would require inspection measures at weapons storage facilities that would be very difficult to negotiate. Since neither side’s air force maintains nuclear weapons onboard bombers, a third approach would treat all nuclear weapons for bombers as nondeployed and thus not counted under the 1,000 deployed strategic warhead limit suggested above. Such a rule, however, might prove unacceptable to the Russians and to the U.S. Senate, which could question a counting method that did not count any bomber weapons as deployed.

A new agreement would presumably maintain a limit on deployed strategic delivery vehicles (ICBMs, SLBMs, and heavy bombers) and a limit on deployed and nondeployed ICBM and SLBM launchers and heavy bombers. Washington might prefer to keep those limits at the New START levels of 700 for deployed strategic delivery vehicles and 800 for deployed and nondeployed strategic launchers and heavy bombers and to implement further warhead cuts by removing warheads from missiles (“downloading”). This would be consistent with the concept of enhancing stability by maintaining a limited number of warheads on a larger number of launchers.

The Russians, however, will almost certainly press to lower the strategic delivery vehicle limit. As noted above, they originally proposed a cap of 500, and some experts believe that current trend lines have the Russians going to an even lower level. Moscow also may seek a lower strategic delivery vehicle limit as a means to constrain U.S. “upload” capacity, as the United States could not return warheads to missiles that were no longer deployed.

Because a strategic delivery vehicle limit of 500 apparently could accommodate planned Russian strategic forces, any reduction in the limit below 700 would initially fall solely on the U.S. side. Under a limit of 600, the United States might retain a notional triad of 40 heavy bombers, 192 SLBMs (16 SLBMs on each of 12 Trident submarines, with two submarines in long-term maintenance and carrying no SLBMs), and 368 ICBMs. One could conceive of a notional force within a limit of 500, but any limit below the New START level of 700 would force the Pentagon to make painful choices among the three legs of the triad. Whether a limit below 700 would be acceptable should depend on what Russian concessions U.S. negotiators could secure in a new agreement.

Assuming the sides could agree on some level as the limit on deployed strategic delivery vehicles, the related issue of the limit on deployed and nondeployed ICBM and SLBM launchers and nuclear-capable heavy bombers should not prove difficult to resolve.

Nonstrategic Nuclear Warheads

Obama has indicated that the United States will seek to address nonstrategic nuclear warheads. Doing so will pose a very difficult challenge, as the Russians have a large numerical superiority and see those weapons as offsetting what they view as conventional disadvantages vis-à-vis NATO and China. The 2009 report by the congressionally mandated Strategic Posture Commission placed the Russian nonstrategic nuclear inventory at 3,800.[4] The Department of Defense plans to retire its nuclear-tipped sea-launched cruise missiles, which would leave a nonstrategic arsenal of some 400 B61 gravity bombs, half of them deployed in Europe.[5]

U.S. negotiators might consider several principles for reducing and limiting nonstrategic nuclear warheads. First, limits should focus on warheads only, as neither side would want to constrain dual-use delivery systems whose primary mission is delivery of conventional munitions. Second, an agreement should provide equal limits on U.S. and Russian nonstrategic nuclear weapons. That said, equal limits may still produce an unequal outcome; it is unlikely that the United States would build new tactical nuclear warheads, so any limit above 400 could mean a de facto Russian advantage. Third, limits should be global rather than regional. Within a global limit, U.S. negotiators might consider “keep-out zones” for tactical nuclear weapons (e.g., prohibiting such weapons from being deployed within a certain distance of NATO-Russian borders).

Moreover, any limits that would affect U.S. nuclear weapons in Europe would require consultations within NATO. This may not be easy, as alliance members appear divided over how NATO should deal with those weapons.[6]

Russia has called for returning nuclear weapons to their home countries; Moscow likely would press to make that part of any follow-on agreement that constrained nonstrategic weapons. The United States may find that it has to weigh such an outcome in the context of the other terms of an agreement, in consultation with allies. NATO reaction to a possible withdrawal of U.S. tactical nuclear weapons could depend on the reduction that would be achieved in Russian nonstrategic weapons. In addition, the U.S. ability to assure NATO allies that extended deterrence could credibly be provided by U.S.-based strategic forces would be important to NATO member states.

Nondeployed Strategic Warheads

Another issue will be how to treat nondeployed strategic nuclear warheads, i.e., those warheads that are not captured by the limit on strategic delivery warheads. Both countries will want to maintain some number of nondeployed warheads as spares. In addition, the United States has kept nondeployed warheads to hedge against Russian cheating, strategic surprise, or unexpected failure in a U.S. warhead type.

Given that the United States will download some warheads from most if not all of its ICBMs and SLBMs in order to meet the New START warhead limit, U.S. strategic forces will have a significant upload capability. The Russians have expressed concern and may seek to constrain that capability. One way to do so would be to apply a numerical limit on nondeployed strategic warheads.

A limit in the range of 1,000 to 1,500 would result in a reduction in the current number of U.S. nondeployed strategic warheads. The acceptability of that would be affected by factors such as the need to hedge against warhead design failure and the related question of revitalizing the U.S. nuclear weapons complex. The administration proposes to spend more than $80 billion over the next 10 years to modernize the nuclear infrastructure. As the nuclear weapons complex becomes more robust and capable of addressing possible warhead problems, the U.S. military could maintain a lower inventory of nondeployed strategic nuclear warheads.

An alternative but less ambitious approach would not apply a numerical limit to nondeployed strategic warheads, but simply limit them to certain locations, ideally away from ICBM, ballistic missile submarine (SSBN), and heavy bomber bases. The approach also might require data exchanges and updates. The goal would be to facilitate detection of any effort to move nondeployed warheads to ICBM, SSBN, or heavy bomber bases.

A Single Nuclear Warhead Limit?

If the next negotiating round addresses nonstrategic and nondeployed strategic nuclear warheads as well as deployed strategic warheads, the sides might consider negotiating a single limit to cover all nuclear weapons, except for those retired and in the dismantlement queue.[7] There is logic to such an approach. In most cases, a principal difference between a strategic warhead and a nonstrategic or tactical warhead turns on the range of the delivery vehicle rather than on characteristics of the warheads themselves. The B61 bomb, for example, has both a strategic and tactical variant.

One possibility would be to have a single limit on all nuclear warheads with a sublimit on deployed strategic warheads. This would allow the sides the freedom to choose what mix of nonstrategic and nondeployed strategic nuclear weapons they would maintain over and above the limit on deployed strategic warheads. For example, if the sides agreed to an overall limit of 2,500 nuclear warheads with a sublimit of 1,000 deployed strategic warheads, the United States might choose to keep more nondeployed strategic warheads, while Russia kept a larger number of tactical nuclear weapons.

Conventional Weapons

The Russians could raise the issue of long-range, conventionally armed precision-guided weapons, other than conventional warheads on ICBMs and SLBMs, which would be captured by New START, and their impact on the strategic balance. The Russians will closely track U.S. development of systems such as the planned hypersonic glide vehicle, which is boosted to high velocities and then “glides” through the upper atmosphere to its target. U.S. officials have stated that this system would not be captured by New START’s limits. Depending on how it develops, the Russians may seek to limit it in a new agreement. A current focus of Russian concern is the many hundreds of U.S. conventional cruise missiles, which some Russian experts worry could be used to attack Russian strategic forces, including ICBM silos.

The United States will resist limiting conventional weapons, other than conventional warheads on strategic ballistic missiles, in any New START successor. Russian concern about conventional cruise missiles may be overblown. This could be a topic for informal talks between U.S. and Russian military officials. Some transparency about the capabilities of these weapons might assuage Russian concerns and reduce the chance that they could emerge as a problem in the next negotiation.


The monitoring provisions of any new agreement should build on New START. A new agreement thus should provide for a detailed data exchange; notifications; unique identifiers for ICBMs, SLBMs, and heavy bombers; and on-site inspections.

U.S. negotiators might revisit some New START measures. For example, would the sides, in the interest of increased transparency, want to add a requirement that the data exchange specify the number of warheads on each deployed ICBM and SLBM? That information is not provided under New START until an inspection team arrives at an ICBM or SSBN base, and then it is provided only for the deployed missiles at that base.

U.S. officials could revisit the telemetry question with the aim of securing access to all telemetry from ICBM and SLBM tests. A New START follow-on treaty would likely be in effect until 2025 or 2030, encompassing the time when the U.S. Air Force begins to test a new ICBM, as opposed to now when only Russia is testing new strategic missiles. That might give U.S. negotiators leverage to persuade the Russians to share telemetry on all tests.

If the sides agreed on limits on nonstrategic nuclear warheads or nondeployed strategic nuclear warheads, monitoring those limits would pose daunting challenges, as the task would be to confirm numbers of warheads not associated with (more easily detected) delivery systems. U.S. officials should consider proposing that all nonstrategic and nondeployed strategic warheads be stored at declared centralized storage sites, except during prenotified transfers and perhaps temporary deployments. This would mean that only strategic warheads on ICBMs and SLBMs or located at air bases for nuclear-capable heavy bombers would be deployed or readily deployable.

The consolidation of most if not all nonstrategic and nondeployed strategic warheads at declared central storage sites could provide a monitoring opportunity. A treaty could require the United States and Russia to declare the location of each of their storage sites for nonstrategic and nondeployed strategic warheads—such information likely is already known by the two sides—as well as the number of nuclear weapons stored at each site. There could be an exchange of site diagrams showing the location of weapons storage bunkers, bays, or other chambers at each site, with provisions for on-site inspection. An inspection team arriving at a storage site would be told the number of nuclear weapons in each bunker, bay, or chamber and could then choose one or perhaps more for inspection to confirm the number. The sides would have to work out detailed procedures so that the number of weapons could be confirmed without exposing sensitive design information.

As for weapons outside of the storage sites, neither the U.S. nor Russian military is likely in the near future to be ready to accept an “anytime, anywhere” challenge inspection regime. National technical means might detect indications of nonstrategic nuclear weapons outside of storage areas, which would be a treaty violation unless prenotified, but the odds of detection would not be high.

The result of such monitoring provisions would be a two-tiered verification regime. The sides would have fairly high confidence in their ability to detect militarily significant violations of the limits on deployed strategic systems, including deployed strategic warheads. They would have less confidence in their ability to detect violations of limits on nonstrategic or nondeployed strategic warheads. In the end, accepting such an imperfect regime would provide for some constraints on and some monitoring of Russian tactical nuclear weapons. The experience gained in implementing such monitoring could provide a foundation for developing a more effective verification regime in the future.

Third-Country Nuclear Forces

Whether to include third-country nuclear forces, particularly those of China, France, and the United Kingdom, would depend in large part on the levels agreed for U.S. and Russian nuclear forces. Washington reportedly would like one more round involving only the United States and Russia. That will affect the levels that U.S. negotiators propose, as the Russians are unlikely to agree to reduce too far—they almost certainly would not agree to go to a level below 1,000 deployed strategic warheads—without addressing third-country forces.

If third-country nuclear forces were to be included, there are several options for doing so. One would be to multilateralize the U.S.-Russian negotiations and bring in, initially, China, France, and the United Kingdom. Given differences in nuclear force postures and policies, such a five-sided negotiation would be complex, assuming that third countries agreed to participate at all. An alternative would be for the United States and Russia to negotiate a bilateral nuclear reductions treaty but to condition its implementation on China, France, and the United Kingdom accepting some kind of numerical constraints. A third approach would entail informal consultations with Beijing, London, and Paris in order to gain transparency regarding those states’ nuclear postures and planned future deployments.

Each of these approaches has difficulties. The most straightforward approach for the New START successor negotiation is to aim for an agreement limiting U.S. and Russian forces only. That, however, would likely be the last purely bilateral agreement, as Moscow in all probability would insist on addressing third-country forces in any next step.

Missile Defense

In the New START negotiations, the Russians in the end settled for recording their concern about possible future U.S. missile defense deployments in a nonbinding unilateral statement. That statement essentially said that Moscow might consider withdrawing from the treaty if it believed U.S. missile defenses threatened its strategic deterrent.

The Russians almost certainly would raise missile defense in the next negotiation, as a follow-on treaty could have a duration stretching to 2025 or 2030, well beyond the projected 2020 date for deployment of a U.S. Standard Missile-3 interceptor with capabilities against ICBMs. Although it has been long-standing U.S. policy to seek to defend against limited ballistic missile threats, such as those posed by Iran or North Korea, but not against a large, sophisticated ballistic missile attack, the Russians remain wary of U.S. efforts in the missile defense field.

There is no indication that Washington is prepared to limit missile defenses as part of a strategic arms negotiation. Moreover, the administration undoubtedly understands that securing Senate ratification of any follow-on treaty that contained meaningful limits on missile defense would be difficult if not impossible.

To avoid getting boxed into a situation where the Russians demand constraints on missile defense that would provoke Senate opposition to a new treaty, Washington should press to engage Russia on missile defense cooperation. Genuine U.S.-Russian or NATO-Russian cooperation to defend Europe, including European Russia, against third-country ballistic missiles could be a “game-changer.” Day-to-day missile defense collaboration would increase transparency and promote better understanding; it might help persuade the Russians that U.S./NATO missile defenses were not directed against Russia.

Moving Forward

The next round of formal U.S.-Russian negotiations will not begin until New START enters into force, but Washington and Moscow might conduct consultations now with a view to preparing the way for those negotiations.[8] They could discuss their respective concepts of deterrence and strategic stability and explore where their views converge and the implications for future arms reductions. They might begin to work out a common system for categorizing nuclear weapons and disclose to one another the number of nuclear weapons in their arsenals, perhaps broken down into some basic categories. They might begin discussing concepts for verifying possible future limits on nonstrategic and nondeployed strategic warheads. Such consultations would help the sides prepare the ground for formal negotiations.

Once negotiations got under way, U.S. officials should aim for an agreement covering U.S. and Russian forces only, with four numerical limits: 2,500 nuclear warheads; 1,000 deployed strategic warheads; 700 deployed ICBMs, SLBMs, and nuclear-capable bombers; and 800 deployed and nondeployed ICBM and SLBM launchers and nuclear-capable bombers. Depending on the other terms of the agreement, the United States should be ready to consider reducing the latter two limits to 600 and 700, respectively. The verification measures would build on those in New START. Those would be accompanied by a new albeit imperfect monitoring regime for nonstrategic and nondeployed strategic warheads at declared centralized storage areas.

An agreement along these lines would offer a logical follow-on to New START. Although the reduction in deployed strategic warheads to 1,000 might not be as dramatic as some would hope, it would be in the context of a new, overall limit of 2,500. That would mean a 50 percent cut in U.S. nuclear weapons from current levels and a larger percentage reduction on the Russian side.

Like New START, this agreement would offer important benefits for U.S. national security. It would reduce and limit Russian nuclear forces, provide a monitoring regime that would give important transparency regarding Russian nuclear forces, allow the United States to maintain a robust and effective nuclear deterrent, enhance the U.S. position for pressing to strengthen the nuclear nonproliferation regime, and contribute to a more positive U.S.-Russian relationship. Getting there will not be easy. Given the complexity of the issues, it will require several years of intense negotiations in Geneva and a lot of attention from senior leaders in both capitals.

Steven Pifer is director of the Brookings Arms Control Initiative. For a more extensive discussion of the issues covered in this article, see “The Next Round: The United States and Nuclear Arms Reductions after New START” at


1. Office of the Press Secretary, The White House, “Remarks by President Obama and President Medvedev of Russia at New START Treaty Signing Ceremony and Press Conference,” April 8, 2010,

2. U.S. Department of State, “Annual Report on the Implementation of the Moscow Treaty 2010,”

3. Robert S. Norris and Hans M. Kristensen, “Nuclear Notebook: Russian Nuclear Forces, 2010,” Bulletin of the Atomic Scientists, January/February 2010, pp. 74-81.

4. “America’s Strategic Posture: The Final Report of the Congressional Commission on the Strategic Posture of the United States,” 2009,

5. Robert S. Norris and Hans M. Kristensen, “Nuclear Notebook: U.S. Nuclear Forces, 2009,” Bulletin of the Atomic Scientists, March/April 2009,

6. For a discussion of allied views on the U.S. nuclear presence in Europe, see Steven Pifer et al., “U.S. Nuclear and Extended Deterrence: Considerations and Challenges,” Brookings Arms Control Series, No. 3 (May 2010), pp. 19-29,

7. Retired weapons awaiting disassembly could be treated separately by requiring that they be kept at declared storage sites pending elimination, with regular data exchanges.

8. See “Next Steps on U.S.-Russian Nuclear Negotiations and Non-Proliferation,” Brookings/IMEMO paper, n.d., (recommendations from a meeting of Madeleine Albright, Strobe Talbott, Igor Ivanov, and Alexander Dynkin).