F O R U M O N P H Y S I C S & S O C I E T Y
of The American Physical Society 
October 2004



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Teaching About Nuclear Weapons

(Adapted from AAPT Talk, August 3, 2004)

Michael May

With nuclear weapons, there is no effective defense. As a result, unless or until universal disarmament can be achieved, arming to prevent war can only mean nuclear deterrence. The US and the Soviet Union overdid deterrence by a large factor in my estimation, but the general view is that it seemed to work in that particular situation. The key assumption of nuclear deterrence is that the prospect of a single weapon dropped on a single city makes any war of conquest unattractive. Equally important is that the inevitable devastation was obvious to all ahead of time, so that the usual demagogic arguments for war failed and for the most part were not made.

No one pretends that what I have just said about nuclear deterrence is the whole story. For one thing, there are many traps and dangers in the actual practice of nuclear deterrence. What is to be done, for instance, about challenges that don’t directly involve the risk of nuclear war but might do so down the line? There were plenty of such challenges during the Cold War, in Korea, in Berlin, in Cuba, and in Israel.

For another thing, with nuclear weapons as with any other weapon, arming itself causes insecurity. Arms control has been a partial answer for nuclear weapons, unlike any other weapon. The reason is not hard to discern: it doesn’t really matter if one side has one thousand nuclear weapons and the other has two thousand. Both sides are going to disappear if they are used anyway. As a result, the argument for cheating or escaping out of an arms control agreement is much weaker.

A third problem is the one I personally started out with. Planning new ways to kill people, no matter how disguised in high policy language is at least morally questionable if not worse. Back in 1983, the US Conference of Catholic Bishops came up with a statement on nuclear deterrence that did not quite condemn it as a temporary measure, though it condemned it as a permanent basis for policy. Unfortunately it has become just such a permanent basis. Other organizations, religious and secular, have similarly tried to come up with some moral stand that would be realistic in the short-term and yet in keeping with morality and good sense in the longer term, without notable success.

The best thing that came out of those efforts has been a reminder that peace is a positive task to work on. Although arms control is useful, peace is not built by doing away with some number of weapons: weapons can easily be rebuilt in times of stress, leading to even more dangerous situations than we have now. Peace is built through the positive incentives and institutions that cause people to prefer it to war. Nuclear issues have the advantage of making the long run a little clearer than it usually is. You can get a little more of a hearing when you point out that nuclear weapons could explode in your neighborhood than when you point out that our consumption patterns are likely to lead to our extinction for instance, especially since September 11.

First of all, there is no way to deal with the policy and the moral issues without understanding the technical background, at least to the extent that (as I tell students), the politicians representing them, their staff, and the executive leading private companies involved must understand them. The technical knowledge is essential in itself and it also provides a common basis for broader discussion.There are a few major topics under the heading of nuclear issues, and each has an underlying technical component. The dangers are nuclear terrorism, launch of a nuclear weapon owing to warning system failure, and nuclear war, in any of several forms. The positive side includes nuclear energy if it is done right, nuclear medicine and industrial applications.

Probably the most likely form of nuclear terrorism is a dirty bomb, or radioactive release device in the current lingo. There are millions of radioactive sources, of which a few hundred thousands around the world could constitute a real danger. Hundreds or more are lost every year. Dispersing a harmful quantity of radioactive agent into high explosive is not the easiest job in the world, but there doesn’t have to be a lot of radioactivity in order to cause problems.  The major problem is not immediate radiation casualties but cleanup. Understanding why this is so leads to a discussion of what and where radioactivity is and how it harms us in enough quantity. It also leads to a discussion of standards: whether EPA standards would be appropriate in response to a dirty bomb attack, what problems responders and authorities face in the coordination exercises they do to get ready and would face in case of a real attack. These problems range from when and where to evacuate and when to go back, all the way to how to provide disposal for large amounts of contaminated materials. We ran into those problems in working on the Topoff 2 coordination exercise last year, which assumed that a dirty bomb had gone off in Seattle.

Nuclear terrorism can also take the form of attack on a nuclear facility, such as a reactor, a spent fuel pool, or one of the very large fixed hospital radiation facility. Those are very hard targets to hit, which can be demonstrated readily, but that in turn leads to discussions of insider threats and personnel assurance, which constitute the main threat.

Potentially most disastrous, of course, and also less likely, at least we hope, would be a nuclear explosion.  A numerical understanding of what the kill radii and the fallout patterns are can lead to an evaluation of suitable policies better than the TV specials that could be seen as propaganda by the visually sophisticated students of today. The other essential technical understanding is about the materials needed to make a nuclear weapon, the plutonium and highly enriched uranium. Many thousands of tons of these materials exist, often under poor or unknown security in states where the US has little access and it takes only a few kilograms to make a weapon. The material is most accessible in the excess weapon stockpiles, but there is also plenty buried in the currently highly radioactive civilian spent nuclear fuel and some still in research reactors around the world.

This technical background leads to the most serious security issues of today:

  • safeguarding nuclear weapons materials,
  • eliminating the nuclear black market,
  • reducing US and Russian stockpiles,
  • preventing nuclear proliferation
  • getting away from the hair-trigger nuclear posture that the major nuclear powers still have and that relies, at least in the Russian case, on an inadequate warning system that has failed before.

It also leads to the need for an understanding of risk as the product of likelihood and consequences, and what is to be done when neither is well known.

These issues bring up both terrorism and war, state actions and non-state actions.  A lot of work has been done on all of them. Reviewing this work, from the non-proliferation regime, its achievements and problems, to the Nunn-Lugar programs, to the ongoing discussions with Iran and North Korea, to the recent proposals of President Bush and IAEA Director General ElBaradei aimed at enforcing non-proliferation and breaking any link between terrorists and state-owned nuclear weapons, these things constitute the core of any course on nuclear issues.

These methods seem legalistic but today we face much more difficult situations than Iraq. We don’t have good military options to prevent proliferation in Iran or nuclear buildup in North Korea or for securing Pakistan’s nuclear weapons, let alone the dangerous materials in the former Soviet Union. The non-military tools we have with these countries and also with allies, such as Taiwan and other East Asian countries who may want nuclear weapons if North Korea gets them, take a while to implement and are subject to the vagaries of the world situation. This is not a problem that is going to go away.

These problems have been worked on for many years and none has been solved. Since we are dealing with our survival or at least the potential for grave damage, the question will come up as to why this is so. Senator Nunn, speaking of the programs to secure nuclear weapon materials in the former Soviet Union that he helped start, recently asked about the ongoing delays and funding shortages: “If this is not the most important security program we have, what is more important? And, if this is the most important, why is it going to take twenty years to get it done?” Working through the answers to that question is among the best thing we do with students. There are some immediate answers. One is narrow bureaucratic interest on all sides. Another is the very size of some of the problems, such as controlling radioactive sources worldwide, or securing shipping containers of which millions come into and out of the US and other countries every year. Part of our nuclear issues seminar is a field trip for students to see what research is being done on the problem of detecting highly enriched uranium or plutonium in a 40-foot shipping container. Still a third obstacle is that countries such as Pakistan, Israel, Iran and North Korea genuinely and for good reasons view themselves as threatened, either or both by their neighbors or the US.

That leads to a couple of more general lessons for discussion. One is that most of the time most people will do business as usual. That means the only way to deal with the dangers we face is for business as usual practices to become adequate. In many of the cases we are talking about, they are not, just as the US intelligence system was not adequate to the dangers of terrorism, and for similar reasons. Emergency actions can be taken if the motivation is sufficient, but business as usual practices are entrenched and very hard to change. Einstein famously said in 1946, unless we change our modes of thinking, we will drift toward unparalleled catastrophe. Drifting is the right word, and we may indeed be so drifting.

Another observation is that, while nothing concentrates the mind as the prospect of being hanged, the memory that we or our institutions did something wrong seems to pass quickly while the memory of grievances, real or imagined seems to last forever, in part because it is cultivated by some politicians, The United Nations was created after two world wars, two nuclear bombings of cities, and a horrible history of massacres and repressions, yet it was not supported well enough to prevent many bloody subsequent wars. On the other hand, after the Soviet Union got the bomb, talk of pre-emptive nuclear war ceased and nuclear deterrence held sway for the remainder of the Cold War. The nuclear hangman was perceived to be at hand. Today, terrorism-relevant information is said to flow more easily now through the maze of the intelligence organizations, but reforming the organizations themselves remains a distant goal. The Bush proposals for counter-proliferation outlined above came after the public surfacing of the AQ Khan nuclear black market. Some actions have been taken, notably Senate ratification of the additional protocol for safeguarding nuclear activities and a UN resolution criminalizing nuclear trade that could lead to proliferation.  But a decade-long sustained effort is needed to accomplish the rest.

This type of discussion is a necessary part of teaching about nuclear weapons. It leads far from the technical points briefly noted above, but it must be based on both those technical points and the actual history of what people and countries did in response to the nuclear threat. There is a pattern as to why states obtained or refrained from obtaining nuclear weapons. It is made clear by looking at that history. Insecurity and fear are the dominant motivation. Prestige and influence are next, but there would be no prestige or influence associated with nuclear weapons if nuclear deterrence, which the US and the Soviet Union pioneered, had not demonstrated its effectiveness, at least within the context of the Cold War. Biological and chemical weapons, for which there are defenses and which have not proven themselves as deterrents, possess no such prestige.

From that pattern, another observation emerges. Today, a country like Malaysia can, however unwittingly, export key centrifuge components as part of a nuclear black market ring. Isolated, poor countries like North Korea and earlier South Africa can make nuclear weapons. Yet, most of the measures we have looked at are in the nature of limitations or prohibitions on the tools and technologies needed to make the weapons, supply-side measures in other words. Supply-side measures are bumps on the road nowadays, useful, even necessary, but not enough. Somehow, the demand for nuclear weapons must abate, in the regions that now concern us as it seems to have in regions like say Scandinavia   What are the features of countries that seem to have no demand for nuclear weapons although they have the capability? Does the world have to change to be like them before the proliferation problem and with it the terrorism problem is solved? Nuclear terrorists need a state to cooperate or at least shelter them.

One more observation: in the sixties, I gave occasional talks on nuclear weapons at universities. There were often demonstrators in the audience: I would be invited to my own war-crimes trial, for instance. But on the whole most in the audience were willing to engage with the subject. I was director of the Livermore laboratory at the time, and one of my favorite ways to begin was with the question, “Who should work on nuclear weapons?” Then I would list all the answers I could think of on the board: no one, not the US, no one but the US, only the Permanent Five members of the UN Security Council, in any case not the University of California, where I often spoke, or on the contrary only the University or similar non-profits, etc,  I would invite the audience to comment on their choice or make a different one. Of course, there was no good choice that could be put into practice at the time, though there were better and worse choices. I think we have a better opportunity now and I think we are not taking it, but that is just my opinion.

My concluding observation is that there is no moral or ethical solution or approach to these problems that is not based on an understanding of the details, both human and technical. Anything else, any a priori choice is at bottom fraudulent. That is the best argument for continuing to teach and learn about these matters of course.     

There are many opportunities to do that, at least with regards to terrorism. Courses in schools and universities are only some of them. We have held meetings and a workshop bringing together first responders, such as police, firemen, emergency medical people, media people and local officials with scientists who have a background on one or another aspect of the terrorism question. It is usually welcome, although everyone has a demanding day job to do as well. We have participated in critiquing coordination exercises for terrorism response and in other such activities. Education at the grass roots level on all the questions I outlined and more is essential if the effects of an attack are going to be alleviated.

It is more difficult to educate at the level where decisions relevant to nuclear proliferation, counter-and non-proliferation, and nuclear armaments and arms control are made. The present decision-makers seem to be isolated from constructive alternatives. Perhaps the best we can do here, aside from op-ed and similar pieces, is to educate in a realistic manner the people who will make these decisions tomorrow, and to pray that they get the chance. The key to getting credibility with them is realism. Students today grow up in an atmosphere of unrestrained advertising and show business masquerading as political discourse. In my experience they welcome something better and more demanding if they are given some reason to make the effort.

Michael May
Professor (Research) Emeritus
Engineering-Economic Systems and Operations Research
Center for International Security And Cooperation
Encina Hall
Stanford University
Stanford CA 94305-6165
Email:  mmay@stanford.edu
Phone:  (650) 723-9733
Fax:    (650) 724-5683

The Need for Scientific Literacy in a Challenging Era

(Adapted from AAPT Talk at Sacramento, CA August 3, 2004)

Sidney Drell

      I have always felt that the scientific community has a special responsibility to be alert to the implications and practical uses of our progress in understanding nature.  We bear an obligation to assist society, in its political deliberations, to understand the potential benefits and risks and to shape in beneficial ways the applications of scientific progress for which we are responsible.  Though it need not be fulfilled by each individual scientist, this is a moral obligation of the community as a whole, including scientists engaged in basic research and in applied industrial and weapons research and development, and also in teaching science.

      Science and technology are so essential a part of modern life that scientific literacy is assuming an importance comparable to the ability to read and write – which are the more familiar domains of literacy.  Science belongs in the core of the education curriculum no less than reading, writing, and arithmetic – and not just to train scientists, any more than English courses should focus on training professional writers.  Our challenge is to prepare a broad student community to function and contribute as informed citizens equipped to cope with choices and make important decisions that will shape the quality of the human condition in the 21st century.  And education does not take place only in the classroom.  We must also make use of a wide range of effective outreach channels – both printed and electronic – to reach a larger public.

      My talk will consider the role of physicists in issues of national security since that is the area I know best as a result of personal involvement.  But clearly science has been critical in establishing the currently high standards of health and living conditions.

      Throughout history scientists and engineers have contributed to the military strength and ultimate security of their societies through the development of new technologies for warfare.   And throughout history the military and the governmental leaders have called on scientists and engineers to help devise the means to counter or neutralize the technologies developed by adversaries that threaten their national security.

      Looking back to the third century B.C., one recalls the legend of Archimedes designing the great catapult to help thwart the Roman siege of Syracuse.  That was but one example of a variety of fortifications and instruments of war that he contributed.  Perhaps the best known of the great military scientists throughout history is Leonardo da Vinci, who offered to Milan many instruments of war – military bridges, mortars, mines, chariots, catapults, etc. And later Michelangelo spent time as the engineer-in-chief of the fortifications in Florence.

      Equally important to their contributions to developing new military technology, the understanding of the laws of nature by scientists and engineers helps them define the limits of what one can expect from technology – existing and prospective – limits which must be understood when governments formulate military plans and national security policy.  Nature cannot be coerced to meet unrealistic military goals.

      In most of the combatant countries during World War II, there was a total mobilization of scientists into the war effort.  In the United States and Britain they tackled many technical problems, from rockets and antisubmarine warfare to operations research.  Physicists played an especially important role in collaboration with the military in developing microwave radar and the atomic bomb.  And the decisive role of these weapons has been widely chronicled.  This collaboration and its achievements formed the foundation for expanded cooperation following  World War II.

      A new circumstance emerged in the 1950s with the development of the hydrogen bomb.  A factor of 106 more destructive than previous explosives, with its greatly enhanced energy release from a second, or fusion, stage, the hydrogen bomb meant that science had now created a weapon of such enormous devastating potential that, if used in large numbers in a future conflict, it could threaten the very existence of civilization as we know it.  With nuclear weapons, all-out war was no longer an option.  Mass destruction would be inevitable.  We were presented with a fundamental issue:  can civilization survive?  As President Eisenhower said in 1956:  “We are rapidly getting to the point that no war can be won.”  Conventional wars can be fought to exhaustion and surrender, but nuclear war can come close to, in his words, “destruction of the enemy and suicide.”

      New thinking about conflict resolution was urgently called for.  It was essential for us to learn how to resolve our dangerous confrontations and to terminate deadly conflicts before they escalated into a nuclear war that nobody wanted and all too few would survive.

      When the grim realities and futility of nuclear war finally sank in, nations around the world recognized the necessity of working together to prevent one.  With American leadership, they began to cooperate in multi-national diplomatic efforts to reduce the danger and prevent the proliferation of these weapons.  Despite some very frightening crises en route, during the darkest days of the Cold War, we have achieved major successes.  The spread of nuclear weapons has been limited to no more than a handful of nations, a norm of not using them in conflict has been established, and this norm has lasted 59 years since Hiroshima and Nagasaki.  Nuclear weapons have become weapons of last resort.  We recognized that their only use was to deter nuclear attack; to send a warning by their very existence, that, if you do it to us or our friends, the response will be the end of you.

      This new circumstance, and the growing danger of renewed conflict in the developing Cold War, greatly enhanced the importance of cooperation and understanding between physicists and the military and national policy leaders.  A whole raft of new, serious issues had to be explored and understood – not only hydrogen bombs, but additional challenges including worldwide radioactive fallout from nuclear weapon tests above ground, the global effects of large-scale nuclear war, the leap into space with missiles and rockets, and the role of anti-ballistic missile (ABM) systems.  It was also important to communicate with Soviet and other international scientific colleagues to develop a mutual understanding of these issues.  Not surprisingly physicists, who were responsible for creating nuclear weapons and understood the horrors they could create, played a prominent role in efforts to control them and helping to unite the international community in this effort.

      But it is evident that now we are facing new threats in the 21st century, with terrorism and with the spread of advanced technology.  We must deal with rogue nations and despots as well as terrorists whose actions are not limited by what we consider the norms of civilized behavior.  Moreover it is not clear that deterrence will remain effective in all such cases, particularly for fanatical terrorists.  We must also worry about other weapons of mass terror such as biological weapons. As President Bush said:  “The gravest danger our nation faces lies at the crossroad of radicalism and technology.”  The challenge we must address—both technical and strategic—is how to keep these terrible weapons out of the hands of the worst people, and what to do if we fail.  As starting point for considering what needs to be done to meet this challenge, it is useful to begin with a brief review of where things stand today.

      Today only eight nations are confirmed nuclear weapon states:  the United States, United Kingdom, Russia, China, France, India, Pakistan, and Israel, the latter a non-declared nuclear weapon state.  The evidence is unclear as regards North Korea, even though North Korea’s government wishes the world to believe it has them.  Iran has been aggressively building a nuclear infrastructure.  This number of nuclear weapons states is considerably smaller than was anticipated when the nuclear Non-Proliferation Treaty, signed in 1968, entered into force in 1970.  (President Kennedy in the early 1960’s predicted 25 by 2000).  And it hasn’t grown over the past two decades.  This number is even more impressive when on recalls all the nations who flirted with the idea of going nuclear, and those who, in fact, started down the path to nuclear weapons and turned back. [Argentina, Brazil, Taiwan, South Korea, Sweden].  But we are reminded daily by what is happening in North Korea, Iran, and Pakistan, the latter with its extensive nuclear supplier network created by Dr. Abdul Qadeer Khan as well as its precarious arsenal, that the nuclear restraint regime is facing tough challenges.  It has to be addressed from all  angles: diplomatic, technical, policy, and intelligence.

      Thus far the NonProliferation Treat (NPT) been the bulwark in the effort to counter the spread of nuclear technology and weapons to other nations.  It was extended into the indefinite future at the United Nations in 1995 at its fifth and final scheduled five-year review.  At present it has almost universal support:  of the world’s 185 nations, all but four have signed on to this Treaty.  The four are India and Pakistan, who became nuclear after the treaty entered into force in 1970, Israel, who has never explicitly admitted to being a nuclear power, and North Korea, which recently withdrew (Jan. 2003).  Does it still meet our needs of preventing proliferation and keeping the worst weapons from the worst people?  Do we need to modify or toughen its restraints?  The U.S. and Russian commitment to the Treaty, and to fulfilling their obligations under it, was explicitly affirmed by Presidents Bush and Putin in their Joint Declaration at the Moscow summit in May 2002.  It is clear that to sustain and strengthen the non-proliferation regime the leadership and example of the U.S. will be decisive.  The cooperation among all nations – non-nuclear as well as nuclear – will also be crucial.  We must also recognize and deal with the concerns and basic motivations which drive some countries to seek to become nuclear powers.  That requires much more than simply arguing that proliferation is bad for your health.

      I will now briefly discuss major physical and technical challenges to the anti-proliferation effort at present.  The biggest hurdle for states or terrorist entities, that seek to achieve a nuclear weapons capability is getting their hands on uranium ore, the raw material from which to make the nuclear fuel, or SNM.  The ore has to be enriched by isotope separation from 0.7% to 90+% U 235   for a uranium bomb, or it has to be converted into fuel rods to power a reactor producing Pu 239 .  The most important means for minimizing the risk of such societies acquiring a nuclear weapon is to keep nuclear fuel - U 235 and Pu 239 - out of their hands.  For those with no uranium ore on their territory, theft or illegal purchase may be the only way to get it.  Of particular concern in this regard is the large quantity of nuclear materials and nuclear warheads stored in the former Soviet Union in less than ideal security circumstances.

      Their stockpiles are the largest in the world.  As reported in 2002 by the Harvard University Project on Managing the Atom, Russia still has hundreds of tons of separated plutonium and of highly enriched uranium, enough fuel for more than 50,000 nuclear warheads, in addition to its approximately 20,000 warheads that already exist.  Material is reportedly spread across more than 250 buildings at 50 sites.  Warheads are located in more than 60 sites, in more than 160 storage bunkers.  This constitutes a very rich treasure for would-be proliferators, emphasizing the importance of cooperative measures to secure them from theft or sale.

      With the lifting of the oppressive measures that regulated travel and other aspects of life in the Soviet Union, and the deterioration of Russian security services, there is now a need for better systems of protecting and accounting for their vast stores of nuclear materials that remain as a legacy of the Cold War.

      Technology is available to protect this material by installing new security systems, and substantial progress has been made in the former Soviet Union under the Nunn-Lugar CTR program that is funded by the U.S. Congress since 1992 to the tune of very roughly $1B/year.  It is an outstanding example of U.S. statecraft.  But vulnerabilities still remain.  More than half of the nuclear material in the former Soviet Union still remains to be protected by improved security for material protection, control, and accountability; and there is an eager market to get their hands on it.  And many border crossings are unprotected.

      For those with ore available, the challenge is to prevent them from enriching it or producing Pu.

      The May 2002 Bush-Putin Declaration of Moscow that I referred to earlier calls on all nations to strengthen and strictly enforce export controls, interdict illegal transfers, prosecute violators, and tighten border controls to prevent the proliferation of nuclear weapons (and of biological and chemical weapons as well).

      This program presents a considerable intelligence challenge, and also a political one, requiring broad international cooperation to monitor such compliance measures; of obvious importance are activities to produce nuclear weapons in a nation that has initiated a serious covert effort to build one.  To illustrate what is required, consider a nation that has adequate uranium deposits in its territory as well as the technical-industrial base to produce nuclear weapons indigenously.  Let’s assume it chooses to build a gaseous centrifuge plant to enrich uranium to fuel a gun-type driven weapon.  Technology for gas centrifuge machines is widely available.  Such a first generation uranium fission bomb, in a gun-type assembly, was what the U.S. dropped on Hiroshima.  No large reactor to produce Pu 239 is required, nor perfecting the more sophisticated implosion mechanism as needed for a plutonium bomb.  Furthermore, it could be deployed with confidence without requiring an underground nuclear explosive test,  just as we did with the Hiroshima bomb.

      I do not want to imply that building up a functioning nuclear weapons program is a simple task.  In spite of all that is now known and is widely available in the public domain about nuclear technology, it still requires a capital investment in the plant and a substantial effort involving large numbers of trained people with specialized engineering and scientific skills (e.g., obtaining and working with maraging steel needed for very rapidly spinning centrifuges).  Nevertheless, if a proliferating country wished to conceal a gas centrifuge plant capable of enriching enough uranium to fuel several weapons per year, the challenge would not be insurmountable:  the required facility could be contained on a factory floor space of modest size.  The energy requirements are low.  It would require less than a megawatt of electric power input and could be readily built underground.  The large halls at the uranium enrichment facility recently observed at Natanz in Iran – roughly 2 football fields in size – are estimated to be capable of holding over 50,000 centrifuges, enough to fuel a dozen or more uranium bombs per year.  For several bombs per year the plant could be proportionally smaller.  With current widely available technology it would require perhaps 3,500 gas centrifuges, depending upon their efficiency, to produce fuel for just one primitive enriched uranium weapon in a year (14,000 SWUs).  (x10 for 4% U 235 for 1.3 GW Light Water Reactor)

      With more modern gas centrifuge technology, the plant size could be significantly smaller.  This emphasizes the importance of monitoring from the very beginning of the construction, together with insisting on authority for on-site challenge inspections once a suspicious activity has been identified.  This will almost certainly require mandatory full-scope on-site inspection measures beyond authority that the IAEA has currently over all declared sources and fissile materials for peaceful nuclear activities.  It will have to include challenge on-site inspections of undeclared and suspect activities as well, as called for in the Additional Protocol to the NPT that has yet to be acted on by many nations as a requirement for all NPT signatories.  That protocol to the NPT, advocated by the Bush Administration and ratified by Congress, will also require in addition to universal acceptance, enforcement powers to deal with cases where a nation refuses to admit or give access to inspectors.

      These observations give a picture of the scale of effort and difficulty involved in detecting and/or hiding nuclear production activities.  This monitoring problem is a complex one that requires more than just the satellites, or so-called national technical means, circling the earth and sampling all parts of the electromagnetic spectrum from a couple of hundred kilometers up to synchronous orbit.  Onsite inspection, and familiarity with the culture and the language, have become the part of the new intelligence challenge.  We have a measure of confidence in the ability to meet this challenge based on our experience with Iran and North Korea and the fact that their efforts at covert programs have not succeeded for extended periods of time.  But for high confidence in timely detection we will require bringing into effect the Additional Protocol to the NPT strengthened with enforcement authority by IAEA.  This presents one of the really hard problems for maintaining a non-proliferation regime in today’s world, as illustrated in current discussions with Iran and North Korea.

      In addition to the challenge to the non-proliferation regime from nations abroad like North Korea and Iran, as was also the case for Iraq before the Gulf war, there is also an apparent challenge coming from changes in nuclear weapons policy being considered in Washington.  Several voices in U.S. official circles have recently proposed that the U.S. consider developing a new generation of low-yield nuclear weapons for use in limited military engagements – particularly against deep underground hardened bunkers.  These weapons would be considered more useable in such missions by virtue of the reduced collateral damage they will cause from dispersed radioactive debris. Congress appropriated roughly one-half of the funds requested for studying such weapons in FY 2004;  the request for FY2005 is still being debated.

      The Bush administration’s 2002 Nuclear Posture Review states that a “need may arise to modify, upgrade, or replace portions of the extant nuclear force or develop concepts for follow-on nuclear weapons better suited to the nation’s needs.” And the Review highlights a specific need for a class of low-yield earth-penetrating nuclear weapons – or so-called “bunker busters” – “to defeat emerging threats such as hard and deeply buried targets (HDBT)” of military interest being built in many countries.

      Such a policy would be a rejection of the fundamental proposition underlying deterrence and the non-proliferation regime: that the only purpose of nuclear weapons is as weapons of defensive last resort.      

      The idea of low-yield more useable nuclear weapons for military missions such as attacking HDBTs needs quantitative evaluation on technical grounds as to their actual military effectiveness.  It would be foolish to seriously harm our national security by weakening deterrence and the non-proliferation regime in order to achieve nothing more than marginal military value.

      The current interest in the “bunker busters” has been motivated by the growing number of hard and deeply buried facilities being built in a number of countries.  Citing recent government studies, the Nuclear Posture Review states that there are some 70 nations with more than 1,000 known or suspected strategic targets, which are used for storing weapons of mass destruction, protecting senior leaders, or executing top-echelon command and control functions.  Among the underground targets of most concern are very hardened structures built, at depths of 1,000 feet or more, with reinforced concrete capable of withstanding up to 1,000 atmospheres overpressure.

      Destroying such targets requires knowing exactly where they are and then precisely delivering a warhead that can penetrate into the earth without damage before detonating.  The warhead must also have a sufficiently large explosive yield to transmit a strong shock.  The United States after >1000 tests has already designed and tested a variety of low-yield nuclear devices that could be adapted for delivery in structurally strengthened warheads for destroying underground targets at shallow depths.  Recently, it adapted a high-yield weapon, the B61-11 bomb, with yields that exceed a hundred kilotons, in this manner.  A key technical challenge is to develop the means to deliver such a bomb intact to depths of 10-20 feet before detonation.  Detonation at such depths increases, by a factor of 10-20 relative to a surface burst, the energy of the explosion that is delivered into the ground instead of into the atmosphere.  The warhead therefore hits the target – a hardened, buried bunker or tunnel – with a much stronger shock than an identical warhead that is detonated on or above the surface.

      Taking into account realistic limits on material strengths, about 50 feet is the maximum depth to which a warhead dropped from the air into dry rock soil could maintain its integrity until detonated.  This is true even with impact at supersonic speeds.  For the shock to reach down to 1,000 feet with enough strength to destroy a hard target in dry rock, the yield of the warhead must be significantly larger than 100 kilotons, certainly not a low-yield weapon.  As to the collateral damage produced by such bunker busters, particularly if used in or near urban settings which can be the preferred locales for hardened underground targets, the blast of even a very “low-yield,” one-kiloton earth penetrator would eject vast amounts of radioactive debris, and would be quite devastating in a city.  The radioactive contamination from a one-kiloton warhead (just 1/13 the yield of the bomb that destroyed Hiroshima) detonated at a depth of 20-50 feet would eject more than 1 million cubic feet of radioactive debris from a crater about the size of ground zero at the World Trade Center – bigger than a football field.  Indeed the Hiroshima bomb was detonated at an altitude of close to 1,900 feet in order to minimize radioactive fallout by not digging any crater.  And against really deep targets, yields in the hundreds of kilotons would be required.  A nuclear weapon with a yield, Y,  capable of destroying a target 1,000 feet underground – a yield well over 100 kilotons – would dig a much larger crater and create a substantially larger amount of radioactive debris.  (Dimensions scale roughly as Y1/3  and volume and mass of debris closer to Y).

      Accuracy is also crucial and made possible by GPS and laser-guidance.  But the most difficult challenge for destroying hardened underground targets is the ability to locate, identify, and characterize such targets.  The payoff of accuracy in underground target location, not just in delivery of a weapon is enormous.  It is also important to find any vulnerable points such as tunnel entrances or air ducts.

      Nuclear weapons are also of limited value against biological and chemical weapons stored in underground bunkers.  When detonated underground their effective range in destroying the deadly effects of pathogens and gases is limited by the fact that their blast effects extend beyond the area of very high temperatures and radiation they create for destroying such agents.  This area extends not much further than the range of neutrons and prompt gamma rays emitted during the explosion, or only a few meters for a kiloton weapon and increasing only as the cube root for higher yields.  Therefore they would be more likely to spread these agents widely, rather than to destroy them completely.  As an alternative to destroying such localized HDBTs, the United States should pursue effective means to put them out of business – that is, to functionally defeat them – using conventional forces and tactics.  This would required improving the ability to locate and seal off their points of access and exit for equipment, resources, and personnel; and, when possible, to establish area control and denial around them.

      Bottom Line: A decision by the world’s only superpower to develop and test new, and presumably “more usable,” nuclear weapons for new missions as bunker busters would send a clear and negative signal about the non-proliferation regime to the non-nuclear states.  If the United States, the strongest nation in the world, concludes that it cannot protect its vital interests without relying on nuclear weapons in limited war situations, such as against deeply buried targets, it would be a clear signal to other nations that nuclear weapons are necessary for their security purposes too.  The United States could thereby be dealing a fatal blow to the regime in order to provide itself with a capability of questionable military value.

      Beyond the specific technical points I have been making about bunker busters, there are deeper and more difficult policy issues that are challenging this country and other nations: we face the prospect of not only rogue nations, but generally very bad, dangerous people, including fanatical and often suicidal terrorists, attempting to get their hands on nuclear and biological weapons capable of devastating destruction and terror.  What can we do to make sure that if the worst people do succeed in getting their hands on the worst weapons by theft, illegal purchase, or any other failure of our anti-proliferation efforts, that they will never to able to threaten to use them against us?

      Against such individuals whose behavior is not restrained by the norms of civilized behavior, deterrence and containment as we have known them thus far may not be adequate, and a more aggressive policy is required. This is not an idle theoretical question but rather an issue very much on the agenda, explicitly raised in our most recent national security strategy documents. To meet this challenge the United States has adopted a policy of taking anticipatory action to defend itself against emerging threats “before they are fully formed”; that is, we will take preventive military action before the existence of an established threat.  But we have to recognize that the actual implementation of such an aggressive policy of preventive military action comes with serious risks and raises tough new questions.  Against whom, in particular, and when and how, should military force be applied against emerging but not yet fully developed threats of nuclear or biological weapons? 

      Preventive military action requires exquisite intelligence to evaluate the danger accurately and to identify the critical targets correctly.  Our current difficulties and debates about U.S. policy in the mid-East, however you view the choice that the U.S. has made to initiate war against Iraq, are clear evidence of the difficulties of taking such actions.  Most decisions to initiate preventive action have to be made even though there may be big uncertainties, as well as gaps and wrong information on essential facts, a circumstance that may result in divided support and challenges to the legitimacy of the mission, both at home and abroad, if not its outright failure.  That is all the more reason to exhaust all possible avenues of diplomacy before relying on force, when it is deemed necessary, as a last resort. 

      To be sure, it is a very tough order and a frustrating ordeal to engage in patient, multi-national diplomacy with rogue nations that are bent on joining the nuclear club.  And it is even more daunting to get at the roots of what generates fanatical destructive behavior in terrorists.  Furthermore changing such behavior patterns takes a lot of time as well as effort.  In the meantime we have to pursue practical measures that can be effective in the short term in keeping evil despots and suicidal terrorists from being able to threaten us with nuclear and biological weapons of mass destruction and terror.  The terrorist strikes of 9/11 and just two months ago in Spain are warning enough of this need.

      We have several examples from recent history that illustrate conditions under which military force, or the threat of preventive or preemptive action, can be effective: 1) the likelihood of successful retaliation by the potential proliferant is low; 2) the proliferant is viewed by large parts of the international community as a threat to its neighbors; 3) peaceful means of blocking nuclear or biological weapons programs has failed or seems likely to fail.  All three conditions are almost certainly necessary if a proposed use of military force is to gain the broadest possible support, not only for the military action itself but also for the follow-through, economic and otherwise.  However, the simultaneous existence of all three conditions is the exception rather than the rule. As evidence, recall cases where not all three conditions existed, and military force or the threat of force was not credible and was not brought into play.  They include the Soviet Union in the 1950s as it tested and began to deploy nuclear weapons, and China, when it began to move toward a nuclear weapons capability in the 1960s. There were influential voices in the United States that spoke out for preventive war against the Soviet Union in the 1950s, fearing that a Soviet nuclear arsenal would prove devastating for American’s position in the world and for the American homeland itself. A similar discussion took place at high levels of the American and Soviet governments during the Kennedy administration when China was seen to be nearing a nuclear weapons capability.  The discussion led nowhere, another example of the lack of utility of military force under the circumstances then existing.

      In order to halt North Korea’s nuclear programs, it will undoubtedly be necessary to negotiate a non-use of force commitment between the United States and North Korea in the context of a freeze and dismantlement of all North Korea’s nuclear weapons programs. The Clinton Administration’s Agreed Framework of 1994 froze their nuclear reactor and reprocessing activities in return for promises of power for civilian needs and limited economic aid. We now would insist on the return of IAEA inspectors with the authority to inspect the elements of a gas centrifuge facility for enriching uranium components, which North Korea has recently been acquiring in violation of the Agreed Framework, and setting a firm schedule for removing the plutonium, including all spent fuel rods from North Korea, and dismantling its nuclear weapons facilities and program.

      The North Korean leadership is primarily interested in survival and seems to be aware that economic changes will be necessary for that to happen.  Unless the leadership becomes firmly committed to that route and convinced that it will be safe to pursue it – or the present government collapses under the weight of its domestic failures and abuses – the leadership will persist in its development of a nuclear weapons capability.  Crisis will follow crisis until military action, or acceptance of North Korea as a nuclear weapons state, are the only alternatives.

      A broad program of economic cooperation involving North Korea must proceed on a multilateral basis.  And security guarantees should ultimately include North Korea’s neighbors – South Korea, above all.  Since North Korea poses a threat to its neighbors, guarantees must be a two-way street.

      Some issues probably can only be resolved through trilateral talks between the United States, South and North Korea aimed at revising the system created by the armistice agreement of 1953.  Most likely Russia, China, and Japan will also play a prominent role in the diplomatic steps leading to a peace treaty and to other obligations undertaken among the parties, although not all the obligations will be of concern to every party.

      Are the U.S. Congress and the American public ready for this?  With presidential leadership, perhaps so, especially since the alternative very likely will be not only a nuclear-armed North Korea but also the entry of Japan, South Korea, and perhaps Taiwan into the ranks of nuclear-weapon states.   This would affect China, which would affect India, which would affect Pakistan.  An Asian arms race rivaling the Cold War’s U.S.-Soviet nuclear arms race could be the result.

      In addition to continuing the moratorium on underground nuclear explosive testing we should work toward bringing a Comprehensive Test Ban Treaty into force.

      Many nations signed on to the indefinite extension of the NPT in 1995 on the explicit condition that the nuclear powers would cease all nuclear-yield testing.  A U.S. decision to terminate our moratorium since 1992 and to resume testing to produce new nuclear weapons would therefore dramatically undermine the NPT.  Conversely, a U.S. decision to ratify the CTBT that it signed in 1996 and lead the effort to bring the treaty into force would be an effective way of strengthening the NPT and, through it, worldwide anti-proliferation efforts.

      All U.S. allies in NATO, including Great Britain, Germany, and France, have signed and ratified the CTBT, as have Japan and Russia.  Israel has signed the CTBT and is participating energetically in the work of setting up a verification system.  Others, including China, have indicated they will work to bring the treaty into force once the United States has ratified it.  Currently 32 of the 44 nations that have built nuclear reactors, the so-called “nuclear-capable states” that must ratify the treaty for it to enter into force, have done so.  In toto, 112 states have now ratified and 171 have signed.  It is time for the U.S. to reconsider the issue of ratifying the CTBT.  The White House and the Senate should enter into a serious debate to clarify the underlying issues, both the concerns and opportunities.  This debate was not adequately joined in 1999 when the CTBT first came before the Senate for its advice and consent to ratification, and regrettably the Bush administration has thus far refused to reopen the question.

      Why is the United States reluctant?  In addition to the dubious need to develop “concepts for follow-on nuclear weapons better suited to the nation’s needs,” including nuclear earth penetrators against HDBTs, opponents of the CTBT have raised two questions:  (1) “How can we be sure that many years ahead, we will not need to resume yield testing in order to rebuild the stockpile?”; and (2) “How can we monitor compliance by other CTBT signatories to standards consistent with U.S. national security?”

      The answer to the first question is that total certainty can never be achieved.  But the United States can be assured that the CTBT is consistent with the ability to retain high confidence in the reliability of its existing nuclear force for decades.  This conclusion has been demonstrated by a number of detailed technical analyses.  In 1995 a team of JASON scientists working with colleagues from the weapons community, including technical leaders involved in creating the current nuclear arsenal (one of whom, Seymour Sack of Livermore, is a recipient of this year’s Fermi Award),  reached this finding. This conclusion requires the U.S. to have a well-supported, science-based stewardship and maintenance program, as well as a capability to remanufacture warheads as needed. That determination was crucial to the decision by the United States to negotiate the CTBT and sign it in 1996.  Most recently, in August 2002, a panel of the National Academy of Sciences reaffirmed this conclusion.  And in 2001 so did a government sponsored study, led by General Shalikashvili, former Chairman of the Joint Chiefs that addressed strategic a