President Bush's 2002 nuclear posture differs sharply from its predecessors and is relevant to the President's recently repeated assertion that he will strike first against any country that might pose a threat of using weapons of mass destruction.

The main new trend in the posture is that the US will be prepared to use nuclear weapons in a much wider range of circumstances than before. Such an emphasis has not been seen since the days of "flexible response" forty or so years ago, when tactical nuclear weapons were deployed in Europe and elsewhere.

Yet, nuclear weapons don't help much with the kinds of missions the US prepares for, including the ones noted in the posture, such as digging out deep underground facilities that might contain bio-warfare agents. Deep underground facilities are difficult or impossible to destroy without large nuclear explosions that create large amounts of fallout. Nuclear weapons are more suited for use against shallow-buried facilities (of the order of ten meters deep) but even in those cases, Hiroshima-type yields are needed, and complete destruction of the bio-agents cannot be guaranteed. Other uses mentioned to justify the posture are even more marginal in their feasibility.

Given the overwhelming US conventional advantage and the relative invulnerability of the US to all but nuclear weapons, the US nuclear posture should aim at minimizing the chances of nuclear weapons spread rather than seeking marginal gains with tactical nuclear weapons. Nuclear weapons are equalizers. Why bring them back into the forefront of regional problems, whether in the Middle East or anywhere else?

Increasing the US nuclear threat will increase the motivation of adversaries, big or small, to improve and extend their own nuclear force, or to get one if they don't already have one. The US cannot subsequently be confident that it will be the only power to use or threaten to use nuclear weapons. There are now several demonstrations of the relative ease with which states can acquire nuclear weapons. North Korea, a poor nation of 17 million people, made and separated with little help enough plutonium for perhaps one or more weapons. South Africa made at least six weapons with essentially no help. Other cases tell the same tale.

The nuclear genie is long out of the bottle and the relative stability that characterized the Cold War is also gone. Instead, the US has been pursuing an aggressive strategy of military expansion around the world and ever closer to other states' vital interests. Quite apart from the wisdom of that strategy, is it wise to couple it with an increased nuclear threat to possible adversaries, as the posture does?

In the past, the existence of a real or putative nuclear threat has been a serious motivation for states to improve and extend their own nuclear force, or to get one if they didn't already have it. That was true of the US, USSR, China, and others. The US, as the world's strongest and least vulnerable major power, should pursue a strategy that minimizes the most serious risk rather than increase it for marginal, and questionable, benefits. The posture implies a strategy that does the opposite.

A nuclear posture better suited to our times would recognize these changes. It would lay the policy basis for the following difficult, long-term, but necessary steps:

1. Minimizing the demand for nuclear weapons, focusing on Asia. Asia contains most of the world's population and might, in a few decades, have most of its wealth. Three states there (four if Israel is included) have nuclear weapons; several more could readily have them. The US nuclear posture should provide US initiatives toward a more stable security order there, one in which peaceful states will not be threatened by nuclear or potentially nuclear rivals. The Non-Proliferation Treaty provides a basis -the only existing basis- for such an order, but it needs to be updated with more inducements in the way of technical cooperation and reassurance, and more clearly defined internationally agreed sanctions if the treaty is disregarded. The US nuclear posture in essence forswears the lead in this endeavor.

2. A pattern for nuclear arms reductions that would include eventually limitations on all arsenals. Openness here is as important as numbers. The US and Russia have most of the weapons but, after the first hundred or so survivable weapons, it matters less and less how many a state has. An internationally recognized framework is needed that can be applied to the regions of the world where nuclear rivalries threaten. Instead, the US has gone the other way, with a sketchy US-Russia agreement that delays the time scale for reductions and does not provide any precedent for international agreements on inspections.

3. A strategy for addressing the problem of nuclear terrorism. The most serious dimension of that problem--the possibility of a terrorist nuclear weapon --is closely related to the proliferation of nuclear weapons and capabilities. Any strategy to avoid that has an important international dimension. Hundreds of tons of weapons-grade uranium and plutonium, most of it surplus in the US and former Soviet Union from the Cold War, need to be better secured and accounted for. A solution to the problem of keeping nuclear weapons and materials out of the tens of millions of shipping containers that crisscross the world requires international cooperation on standards, procedures, cost sharing, and inspections. A good start has been made toward these goals, mainly through the Nunn-Lugar programs, but more money and agreements are needed. A modern nuclear posture should establish the policy basis for securing those resources and agreements. There is at present no comprehensive global strategy for securing such vital agreements and establishing the institutions to enforce them. Consistent, high-priority US participation is vital to secure other countries' participation.

4. A strategy for reducing the risks of accidental nuclear launch while at the same time maintaining invulnerability of the reduced deployments. The nuclear posture briefly mentions the "rigorous safeguards" on US weapons systems and proposes to deal with the problem of accidental or unauthorized launch of "certain foreign forces" via nuclear missile defense. That is at best a partial and certainly a distant remedy. Maintaining the human and financial infrastructure for nuclear weapons system will become more difficult in the US as well as elsewhere. Given the relationship among nuclear deterrent forces, the problem cannot be solved unilaterally. A program that would use US technical leadership to improve warning and control for all states threatened by nuclear weapons is also needed. It is needed now in South Asia. Later, it could help limit crises with or among Russia and China, and help prevent proliferation in the Middle East. President Reagan, with a portion of Star Wars, and, before him, President Eisenhower, with Open Skies, had something of the kind in mind. It is time to begin thinking about how this would look in modern form.

In summary, a nuclear posture for a world with more dispersed power centers and more widely available nuclear technology should have more, not less, emphasis on international agreements. President Eisenhower stated fifty years ago that "Only chaos will result from our abandonment of collective international security." That is even truer in today's world than it was then. The present administration seems to have a bias against such agreements, which are slow to bear fruit and do not win votes. That is shown in the posture itself, which states that arms control measures will not stand in the way of nuclear weapons development.

Yet these and other agreements are essential to deal with the dangers of proliferation to unstable states, with the possible use of international trade for terrorism, and with the risk of accidents and unauthorized launch. Nuclear deterrence continues to be needed, but the last thing a modern posture should do is to bring nuclear weapons back into the forefront of regional deterrence.

Ironically, when it has committed itself to the task, the US has used international agreements more effectively than any other nation. The Cold War-- better called a Cold Peace perhaps, since the military lines of demarcation never changed while the safeguarding of Western values and collapse of the Soviet Union were brought about mainly by economic and political instruments-- saw a rise in US power and influence in good part through the use of US-led international agreements in the areas of trade and security, areas that are necessarily related. Now is not the time to give up that approach, especially not in matters relating to nuclear weapons.

The article by Daniel Kleppner, Frederick Lamb, and David Mosher (Physics Today, January 2004, page 30) summarizes the results of the excellent American Physical Society study released in July 2003 on boost-phase options for national missile defense.1 The study represents one of the most authoritative analyses to date on the subject and will enhance the quality of the public debate on missile defense for years to come. However, although I agree with many of the study's conclusions, the overall assessment is somewhat pessimistic, especially with respect to the feasibility of intercepting solid-propellant intercontinental ballistic missiles.

My analysis of airborne intercept options suggests that first-generation airborne boost-phase interceptors (ABIs) carrying 90-kg kinetic-kill vehicles should be effective against liquid-propellant ICBMs. It also suggests that second-generation ABIs with 50-kg KKVs could be effective against solid-propellant ICBMs, provided the ABIs can get within approximately 500-600 km of the ICBM launch site, which is possible for relatively small states such as North Korea.2

ABIs have the advantage that they can contribute to an effective theater missile defense--an important mission given the widespread proliferation of short- and medium-range ballistic missiles. In fact, ABIs are the only form of terrestrial boost-phase intercept that can be effective against very short burn-time ICBMs or short-range ballistic missiles because, if necessary, ABI launch platforms can fly over an opponent's territory. Neither ground-based nor naval-based interceptors have that option.

One should also note that ABI systems pose very little threat to the strategic nuclear forces of the five major nuclear powers; hence, they are not nearly as destabilizing as other forms of missile defense. To the extent that one takes seriously the rhetoric of sharing US ballistic missile defense technology, ABI systems can be transferred because they do not threaten US or allied strategic forces.

The difference between my conclusions and those of the APS study arises from different technical assumptions that result, in my case, in greater intercept ranges. In particular, I assumed that an airborne X-band radar can be built within the next decade, which, for favorable geographies like North Korea, can reduce target-detection and tracking delays by as much as 10 to 15 seconds compared to those in the APS study. I also made the assumption, based on the burn times for existing US and Russian solid-propellant ICBMs, that solid-propellant ICBMs have a nominal burn time of 180 s; the APS study assumed a 170-s burn time based on US solid-propellant submarine-launched ballistic missile technology. Also, airborne missiles can accelerate faster; hence, they can have higher average flight speeds compared to surface-based interceptors (on which the APS study focused) because the drag force is lower at high altitudes.

Nevertheless, solid-propellant ICBMs are very difficult targets. Successful intercept will require sensor architectures that push the limits of target detection and tracking, and large (1500 kg), high-speed (6.0 km/s ideal velocity) two-stage airborne interceptors carrying lightweight KKVs. While 50-kg KKVs stretch the limits of what currently is possible, solid-propellant ICBMs stretch current offensive threat possibilities. Neither may be far-fetched 10 years from now.

ABIs do have drawbacks. However, none of them are so severe as to eliminate ABIs from consideration as a viable component of a future US missile defense architecture. In fact, airborne intercept is probably the most attractive boost-phase missile defense option.

Preferences regarding boost-phase ballistic missile defense often have more to do with different threat assessments, operational and political issues, and cost than with technical disagreements. I see no serious technical barrier to an effective ABI system. Nevertheless, the decision to proceed with any form of ballistic missile defense, ABIs included, should be based on an assessment of the system's priority relative to such other important US security concerns as countering terrorism and modernizing conventional forces. From this perspective, the US currently is spending too much on ballistic missile defense.

References

1. D. K. Barton et al., Report of the APS Study Group on Boost-Phase Intercept Systems for National Missile Defense: Scientific and Technical Issues, July 2003; available at http://www.aps.org/public_affairs/popa/reports/nmd03.cfm.

2. See D. A. Wilkening, Science and Global Security, (in press).

Those advocating nuclear arms control and nonproliferation have few reasons for optimism and many reasons for concern, with obstacles including a lack of public interest in the issue; inadequate security controls at facilities storing nuclear-weapons materials; the threat posed by rogue nations such as Iran and North Korea; and the Bush administration's opposition to the Comprehensive Test Ban Treaty banning nuclear weapons testing.

These and other challenges were explored at a special CISAC workshop on "Arms Control and Nonproliferation: Past Triumphs, Future Prospects," held June 1 at SIIS. The event honored George Bunn -- a nuclear nonproliferation pioneer and consulting professor at CISAC -- on the occasion of his 79th birthday. The workshop, which drew more than 120 attendees, was moderated by CISAC co-director Christopher F. Chyba and featured presentations by four expert panelists who have worked closely with Bunn. They included his son Matthew, a senior research associate for Harvard University's Project on Managing the Atom.

As the first presenter, Matthew Bunn discussed the problem of inadequate security systems to prevent the theft of weapons-grade nuclear materials. Because there are no worldwide standards for protecting such materials, many nations devote inadequate resources to the task. Bunn showed slides of nuclear materials storage facilities with primitive locks, flimsy seals and broken-down fences. He cited Russia as the largest threat, because it has the world's biggest stock of unguarded nuclear-weapons materials. He urged international standards for safeguarding nuclear materials; renewed discussion with Russia on the issue; and the removal of nuclear material from sites where adequate security is not feasible.

In the second presentation, Thomas Graham -- a senior U.S. diplomat who has negotiated numerous major arms-control agreements -- said the nuclear Non-proliferation Treaty was not meant to forever discriminate between nuclear "haves" and "have-nots." Instead, it was designed so that those without nuclear weapons would benefit by receiving peaceful nuclear technology from weapons-producing nations, and guarantees that they would not be attacked. But when the United States shirks its nonproliferation obligations -- as it has done by rejecting the Comprehensive Test Ban Treaty and taking steps to develop new nuclear weapons -- the entire regime is threatened, Graham said. He cited Pakistan and North Korea as the biggest nuclear threats, and said the United States must engage in direct negotiations with the latter.

The next presentation, by Daryl Kimball -- executive director of the Arms Control Association -- addressed prospects for the Comprehensive Test Ban Treaty. Though the treaty has been signed by 171 nations including the United States, it has been ratified by only 113 of those nations -- not including the United States -- and must be ratified by 12 more of the 44 designated "nuclear-capable" nations before the treaty can take effect. Kimball discussed the Bush administration's opposition to the treaty, noting that Bush has sought to remove it from the Senate's agenda. Still, Kimball said he's optimistic that the treaty will ultimately be ratified by the United States and will take effect. He cited increasing international pressure on CTBT "holdout states," and a recent U.S. poll showing that public support for the treaty is at its highest level ever, 87 percent.

John Rhinelander, an attorney who helped negotiate the ABM Treaty and SALT I agreements, discussed the prospects for nuclear weapons in space. The weaponization of space is supported by the Bush administration, he noted, and is a real possibility if the United States follows through on its missile defense program. He predicted that President Bush, if re-elected, would continue to pursue weapons development in space, but said Kerry seemed unlikely to do so if elected.

During a question-and-answer session following the presentations, the panelists offered perspectives on why it is so difficult to get the public's and lawmakers' attention on nuclear non-proliferation issues. The panelists agreed that since the breakup of the Soviet Union, most Americans -- including lawmakers -- no longer perceive nuclear weapons as a serious threat, and they have little knowledge about the existing quantity of nuclear weapons. Matthew Bunn said the problem is, "there is no one whose reelection depends on reducing or securing nuclear weapons." He said nuclear non-proliferation could best be promoted by tying it to the issues of terrorism and homeland security. Rhinelander and Grahm advocated holding Congressional hearings on the issue for the first time in 20 years.

Regarding Israel, India and Pakistan, Graham said those nations -- which produce nuclear weapons but have refused to join the NPT regime -- cannot continue to remain outside the regime. He proposed that the three nations be allowed to join in limited form, in exchange for accepting basic limitations such as no first use and no nuclear testing.

Throughout the event, Bunn was praised by the panelists and moderator; Chyba described him as "the personification of the best that CISAC strives to be." Bunn was the first general counsel for the U.S. Arms Control and Disarmament Agency, helped negotiate the nuclear Non-Proliferation Treaty, and later served as U.S. ambassador to the Geneva Disarmament Conference.