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Research Brief


The United States and other members of the international community are striving to convince North Korea, Iran, and other states to forgo the development of nuclear weapons. If they do not succeed, the consequences for U.S. and allied security could be profound. This research brief describes a RAND Project AIR FORCE study on nuclear-armed regional adversaries, which encompasses an examination of the historical record, evaluations of the strategies and statements of potential nuclear-armed regional adversaries, and politico-military gaming. This analysis suggests that future U.S. policymakers and commanders will need to develop and field capabilities that can prevent (rather than simply deter) the enemy's use of nuclear weapons.

On October 9, 2006, North Korea tested its first nuclear device. Granted, the device's explosive yield (estimated at half a kiloton, or the equivalent of 500 tons of TNT) was not, by the standards of most nuclear weapons, impressive. Nevertheless, the fact that an impoverished nation-state could develop and test a nuclear device in the face of opposition from the United States and all of the other states in northeast Asia is a signal event in international relations. If the United States and other members of the international community do not succeed in their efforts to convince North Korea, Iran, and other states to forgo the development of nuclear weapons, the consequences for U.S. and allied security could be profound.

In anticipation of this future, RAND researchers have been conducting research on the problems that nuclear-armed regional adversaries pose for the United States—security challenges that are quite different from those that it faced during the Cold War and in the post–Cold War era. The Challenge of Nuclear-Armed Regional Adversaries, which presents the findings of a RAND Project AIR FORCE study on the subject, suggests strongly that it would be a mistake to regard nuclear-armed regional adversaries simply as lesser-included cases of more powerful adversaries, such as the Soviet Union during the Cold War.

The research team defined regional adversaries to mean countries that pursue policies that are at odds with the interests of the United States and its security partners, whose actions run counter to broadly accepted norms of state behavior, and whose size and military forces are not of the first magnitude. The category is useful as a means of distinguishing this group of states from larger, more powerful nuclear-armed states, such as Russia, China, and India.

The RAND research team sought to answer important questions about U.S. strategy for Research Brief power-projection operations and about the adequacy of the capabilities that may be available to future U.S. forces. In particular, they addressed these questions:

  • How might future nuclear-armed regional adversaries behave in peacetime, crisis, and conflict?
  • What are the likely ramifications of their development for U.S. security and defense planning?

Motivations of Nuclear-Armed Regional Adversaries

It is important to understand what makes nuclear-armed regional adversaries distinctive from other state adversaries, as well as the motivations for their pursuit of nuclear weapons. Nuclear weapons may be seen as serving multiple purposes. Iran, for example, is thought to be pursuing them for a combination of reasons:

  • to deter military threats or attacks by the United States and, perhaps, others
  • to redress its military inferiority vis-à-vis Israel, Pakistan, India, and Russia—neighboring states that have nuclear weapons
  • to enhance national prestige and influence
  • to shore up domestic political support
  • to ensure the regime's survival in the event of war.

The North Korean regime undoubtedly shares most of these motivations. It might also see its nuclear program as a source of leverage against the United States, Japan, South Korea, and China for extracting economic assistance.

Why Deterrence May Be Problematic in a Time of Conflict

U.S. conventional and nuclear forces will continue to have deterrent effects on the leaders of regional adversary states, such as North Korea and Iran, even if these states field substantial numbers of nuclear weapons. However, defense planners in the United States and elsewhere must begin now to confront the possibility that, in the face of superior U.S. conventional forces, adversaries of this class could consider the use of nuclear weapons as an attractive option (or at least less unattractive than withholding use) in a variety of circumstances during a conflict involving the United States. Several reasons exist for this:

  • Regional adversary nations spend only a small fraction of what the United States does on military forces (less than 5 percent in the cases of Iran and North Korea). This virtually guarantees that any serious conflict involving the United States will end in such opponents' defeat if the conflict stays at the conventional level.
  • Military defeat can have disastrous consequences for authoritarian rulers, who may therefore be prepared to run high risks to prevent it. Facing the prospect of the regime's downfall, an enemy leader may perceive that using one or more nuclear weapons may be the most attractive option available if it might deter the United States and its allies from continuing their military operations.
  • In several recent conflicts, particularly those in Serbia and Iraq, U.S. forces have demonstrated the capability and will to attack enemy leaders, command-and-control assets, weapons of mass destruction, and delivery means. Fears of decapitation strikes or disarming counterforce attacks could lead an enemy leader to perceive that the country is in a use-or-lose situation, thus heightening the pressure to resort to nuclear use early in a conflict.

In short, deterring the use of nuclear weapons by threatening retaliation (a mainstay of Cold War military strategy) could be highly problematic in many plausible conflict situations involving nuclear-armed regional adversaries, for the simple reason that adversary leaders may not believe that they will be any worse off for having used nuclear weapons than if they were to forgo their use.

Improved Capabilities Are Needed to Prevent Nuclear Attacks

This being the case, U.S. and allied leaders confronting nuclear-armed adversaries will want military capabilities that offer far greater assurance that adversaries can be prevented (as opposed to deterred) from using nuclear weapons. This points to demands for forces that can locate, track, and destroy nuclear weapons and their delivery means before they are launched and, above all, active defenses that can destroy delivery vehicles after they have been launched. Today and for some time to come, the emphasis should be on fielding more effective defenses against theater-range missiles that could be used to deliver nuclear weapons.

Unless and until highly reliable means of attack prevention become available, U.S. leaders will be compelled to temper their objectives vis-à-vis nuclear-armed regional adversaries, avoiding conflict with them or using limited military force to minimize an adversary's incentive to escalate to nuclear use.

Research conducted by

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