There may not be a pressing reason to use plutonium fuel before the expected arrival of the breeder reactor in the 1990's, if the breeder then comes into widespread commercial use. The option to reprocess spent fuel is not permanently lost; it is feasible and relatively inexpensive to keep spent reactor fuel in temporary storage pending technical and economic developments.

Such economic considerations may not deter a government from seeking the ability to reprocess spent fuel and reuse its products in reactors. For example, some countries resist being dependent on outside suppliers of fuel; and the desire for independence might encourage the decision to engage in reprocessing. This choice, however, would not actually produce independence, because countries without their own uranium and enrichment plants still would have to depend on outside suppliers for the bulk of their fuel.

Greater fuel independence might be sought via a technical alternative to U.S.-type reactors-the heavy water reactor, which burns natural (unenriched) uranium. A nation with uranium deposits might build or buy a heavy water plant and build heavy water reactors and possibly a reprocessing plant. This heavy water/plutonium reuse fuel cycle would not produce particularly inexpensive electric power, but it would be a potential danger because it could supply the material for a large number of nuclear weapons. And there could still be dependence on foreign suppliers of heavy water.

In short, nuclear independence-defined as possession of all the components of the fuel cycle-is virtually unattainable for most countries, and would be very costly in any event. Nevertheless, the immediate step toward nuclear independence now contemplated by several countries-fuel reprocessingposes special proliferation risks.

Countries that buy nuclear reactors require assured sources of fuel. The United States, as the world's principal supplier of enriched uranium, has a special obligation to assure its customers that fuel will be available.

What might happen beyond the next 10 years to alter the prospect for plutonium recycle? Forecasting is hazardous. Earlier in the nuclear era it was widely assumed that the world's supply of uranium was so limited that plutonium reprocessing would be used early, and that the breeder reactor would come into widespread use soon after, say by the early 1980s. But prospects for early reprocessing and for the breeder reactor now appear less certain.

Breeder Reactors

In contrast to the relatively modest increase in fuel efficiency resulting from plutonium recycling in light water reactors, the breeder reactor would increase the efficiency of uranium use by some 50 times. It would do this by large-scale "breeding" of fissionable material (usable for civilian power or for weapons) out of nonfissionable uranium. The breeder could increase the dangers of proliferation because it would produce large quantities of plutonium and because large-scale plutonium recycling would be an integral part of its operation (Figure 3).

For the breeder to be economical, its capital costs probably should not exceed those of light water reactors by more than a small percentage; otherwise, its presumed fuel cost advantage could be lost. But breeder reactor costs will not be known until much later in the research and development process. Moreover, it is uncertain whether the future cost of uranium fuel will rise to a level high enough to justify building breeders. Whatever the prospect for the breeder in developed countries, it offers even less potential economic benefit for the less developed countries. Breeder reactors will require large capital outlays and are likely to be economically feasible only when used on a large scale. But less developed countries are generally short of capital and have small electric systems.

The earliest date at which significant numbers of breeders and therefore required plutonium separation could enter commercial operations now appears to be the 1990's. Thus, the breeders do not present as immediate a problem as fuel recycling from light water reactors.

Peaceful Nuclear Explosions (PNEs)

Twenty years ago many scientists hoped that by adapting nuclear explosions to civilian uses it would be possible greatly to improve the efficiency of construction projects and the recovery of natural resources. In the United States the Federal Government and private industry spent some $200 million to explore the feasibility of this technology. As an NPT party the United States pledged to make the potential benefits of this technology available to others as we realized them.

We have not realized these potential benefits. In many cases the enormous energy release of a nuclear explosion has turned out to be less attractive than the finely tailored use of a much smaller amount of energy or than other alternative ap

proaches. The legal, environmental, and regulatory questions raised by peaceful nuclear explosions have added to their impracticality.

During 1975 ACDA released two studies of this technology prepared by contractors drawing on American industrial expertise. The consensus, as stated by the American representative at an IAEA technical meeting on PNES, was that "in general, more work is needed to determine or demonstrate the utility of PNE applications." For various "contained" applications in the U.S. the studies concluded that no widespread commercial use was likely before the 1990's, if then.

The arms control problem for PNES is obvious: the devices are nuclear explosives. As Ambassador Martin, Representative to the CCD, has pointed out, for countries in the early stages of nuclear explosive development, the acquisition of a PNE device is the same as the acquisition of a nuclear weapon.

As we have shown, technical, economic, and public policy considerations introduce substantial uncertainties into the prospects for lead-time-shortening technologies. If these technologies should win widespread acceptance, then nonproliferation efforts will face serious challenges. It may be possible in some cases to improve the timeliness of the warning-and-response process to which safeguards contribute. It also may be possible to keep these technologies under multinational control. But for some technologies it may not be possible to develop meaningful systems of control. If the control systems fail to develop as rapidly as the technologies, the consequences are likely to be substantially increased proliferation.

Turning Points

On May 18, 1974, India became the first new nation in a decade to explode a nuclear device. India asserted that this was a "peaceful nuclear explosion," thus avoiding an unambiguous violation of a 1955 "peaceful uses" agreement with Canada under which India obtained the reactor that apparently produced the material for the explosion. Since May 1974 India has not exploded a nuclear device.

India's explosion has had a major impact on the effort to prevent proliferation. What appears to many to be a successful demonstration of the diversion of civilian materials to a nuclear explosive quite possibly had the effect of stimulating the interest of other countries in obtaining nuclear weapons. Specifically, the security concerns of Pakistan, which has a

nuclear power program but is not a party to the Nonproliferation Treaty, were doubtless heightened. On the other hand, the event jolted individuals and nations into the realization that there was much urgent work to be done to prevent further proliferation, and there has been increased attention to nuclear exports and safeguards as a consequence.

What should the world do when it arrives at such turning points in the effort to retard nuclear proliferation? Over the past 20 years some nations have taken actions that can only be explained as efforts to acquire nuclear weapons options. These actions did not occur at evenly spaced intervals but in a "series" or group of related events. One such series occurred within a relatively short period in the last half of the 1950's. Another series apparently occurred within roughly a year of China's first nuclear test in 1964. A third series may have occurred within a few months of the 1974 Indian nuclear test. Each of these three series changed the dimensions of proliferation; each was a world turning point.

Although safeguards are improving, nations will continue to have the physical capability to violate them and will be able to construct nuclear explosives. No doubt the international community will continue to improve the legal, technical, and detection barriers to proliferation. But civilian nuclear technology is moving forward too, reducing the critical time for producing nuclear weapons from years toward months, weeks, or possibly even days.

We are at a turning point in our efforts to control and perhaps prevent proliferation. Within a few years, we might see the further shortening of critical lead-time in key countries, perhaps some violation of safeguard agreements, the testing of nuclear explosives by nonnuclear weapon states, or even the reckless export of fissionable material intended clearly for nuclear weapons. Our response must take account of what we now realize-national decisions on proliferation are interlinked, and an action that seems limited in itself may cause literally a global chain of reactions, undermining world stability.

The international community has not yet responded to acts of proliferation with sanctions, but the prospect of such a strong response might assist in deterring such actions. The Secretary of State recently warned that the United States would treat a violation of international nuclear agreements with the utmost gravity. If further proliferation is to be prevented, the world must also view it as grave and act accordingly.

Although strategic weapons consume only a fraction of the military budgets of the nuclear superpowers, they understandably occupy a much larger share of public attention. If these weapons were ever used, the result would be a catastrophe, not limited to any particular region but of global magnitude. It is true that the prevention of nuclear war also requires control of conventional weapons, because the risk of nuclear escalation would increase enormously in the event of a large-scale conventional war. Nevertheless, strategic arms limitation currently has the highest priority in our efforts to limit arms. competition between the superpowers.

Strategic Doctrine

To understand strategic arms control, it is essential to understand the purpose of strategic forces. No possible U.S. military posture could deny the Soviet Union a capability to wreak catastrophic destruction on the United States or its allies. The purpose of our strategic forces is not to make a Soviet attack on the United States or its allies physically impossible, but to make the consequences so unacceptable for the Soviet Union that Soviet leaders will be dissuaded from ever launching one. This is the doctrine known as deterrence. It is a doctrine which emphasizes preventing rather than fighting-wars whose destructiveness would be so great as to render the notion of "victory" illusory.

For the foreseeable future, the abolition of national nuclear forces is not a realistic objective of international negotiations. In U.S. policy, therefore, the objectives of strategic arms control are complementary to the objectives of strategic doctrine. That is to say, the purpose of strategic arms control is to strengthen nuclear deterrence (if possible at lower levels of forces), to render it more stable, and to make an accidental nuclear attack less likely.

The issue of what is required to strengthen deterrence is complex and frequently controversial. This is so because deterrence depends on the psychological state of mind of both adversaries and on how they interact with each other. It is sometimes thought that deterrence begins and ends with maintenance of a retaliatory capability potentially able to

devastate the cities and kill most of the urban population of a potential adversary. This is an inadequate and frequently misleading conception of the purpose of strategic forces. If arms control efforts are to succeed in improving our ability to deter war, we need a more complete understanding of the purposes for which strategic forces are maintained.

It is helpful to recall how U.S. strategic forces have actually evolved since nuclear weapons were first used at the end of World War II. It was clear at that time that nuclear weapons had revolutionized the technology of strategic bombing. However, with the end of World War II there was no obvious military purpose for such massive destructive capabilities. Indeed, for several years the U.S. atomic development program proceeded very slowly. As late as 1947 there was not a single assembled nuclear weapon available to be used by U.S. forces an important fact that belies charges that the United States then exploited its nuclear monopoly. However, as tensions increased in Europe and the possibility of a war with the Soviet Union appeared to grow daily, the United States and its European allies grew more concerned about the overwhelming strength of Soviet conventional ground forces. They hoped that the massive use of air power and the United States monopoly of nuclear weapons would be able to prevent a successful Soviet invasion of Western Europe.

This thinking carried over from the World War II experience the concept of strategic bombing with conventional high explosives. Strategic bombing efforts in World War II were intended to attack the enemy's war-making capability at its source. However, accurate bombing of specific production facilities, fuel supplies and transportation bottlenecks was difficult in the face of enemy defenses. Hence an additional rationale developed for large-scale, indiscriminate attacks which could destroy urban population centers even with highly inaccurate bombing. Such attacks, it was contended, would weaken enemy morale and reduce the population's willingness to support continued warfare. Postwar studies (particularly the U.S. Strategic Bombing Survey) in fact showed that direct attack on warsupporting facilities was by far the more effective strategy and that attacks on the civilian population