Research Brief

Now that the Soviet threat has faded, U.S. deterrent strategy will focus on dissuading regional powers from attacking U.S. interests. These strategies must recognize the motivations and vulnerabilities of such aggressors. In a recent RAND report, U.S. Regional Deterrence Strategies, Kenneth Watman and Dean Wilkening examined the prospects for military deterrence in the post–Cold War era. Working from historical case studies and analyses of aggressor behavior, they assessed how difficult it would be to deter regional aggressors, how credible a deterrent the United States could mount, and what inferences should be drawn for U.S. deterrent strategy. Their findings, detailed in the remainder of this brief, may be summarized as follows:

  • Regional aggressors may be difficult to deter if they expect their hold on power to erode if they do not take risks.
  • The United States may have difficulty convincing such aggressors that U.S. resolve is high, because U.S. vital interests frequently will not be at stake.
  • To compensate for perceptions of weak resolve, the United States should bolster perceptions of its military capabilities, in particular, those contributing to prompt denial of an adversary's military objectives.
  • On the whole, the United States will have to be selective about the situations in which it attempts to deter aggression.

How Difficult Will It Be to Deter Regional Aggressors?

In predicting the actions that a regional aggressor may take in the face of a deterrent threat, it is important to recognize that what may seem to be irrational behavior is seldom so, from the aggressor's perspective. A regime contemplating an attack on U.S. interests will weigh the potential costs and gains from such an attack against the cost or gain from not taking that action. If a state is relatively satisfied with its prospects and is challenging the United States or its allies for the purpose of extending those prospects, the possibility that it will lose instead of gain may be a sufficient deterrent. But if a regime foresees a bleak, deteriorating future for itself and it believes there is some chance—even a small one—of averting further losses by taking action against the United States, it may be rational to gamble.

Such risk-tolerant regimes are not uncommon. Many a Third World government lives with chronic threats to its security⁠—threats that often arise from within the state. Because this instability threatens a regime's hold on power, its stakes are very high and its risk-taking propensities may be much greater than appreciated by U.S. leaders, focused as they are on external threats. Deterring such regimes will thus be difficult and at a minimum will require credible threats to deny the regime's objectives for using force and perhaps to punish it for its aggression.

Credibility has two facets. The first is whether the adversary believes the United States intends to do what it threatens to do. The second is whether the adversary believes the United States is capable of doing it.

Can the United States Convey a Credible Deterrent Intent?

In considering whether the United States really intends to carry out a deterrent threat, an aggressor regime will think about whether the United States is seriously interested in the object of the contemplated aggression. For an adversary to believe the United States is committed to the defense of an ally, this commitment must be selective and established over time—often at considerable expense (both financial and political). Such commitments will thus be few. In many regional crises, the United States may experience some difficulty convincing opponents that its commitment to a regional ally is strong.

If the perception of U.S. interests is weak, the United States can bolster perceptions of its resolve by relying on its reputation. Operation Desert Storm certainly made clear that the United States would defend Middle Eastern oil interests from large attacks. But regional powers understand that intent can change from one administration to the next and from one situation to another. Clearly, the U.S. effort mounted in 1991 to guarantee oil availability in Kuwait was not interpreted to imply that the United States would take military action to defend human rights in Bosnia the very next year.

A regional aggressor may thus consider it unlikely that the United States will move to deter him with military force. To bolster the credibility of deterrence in response to this perception, the United States should create the impression that it has the capability to respond effectively if it so desires.

What Capabilities Are Needed to Strengthen Deterrence?

When they resort to force, regional adversaries typically seek short, cheap wars. Therefore, the most impressive U.S. military forces would be those that could deny a quick, decisive victory. In other words, forces that are in the region or that can deploy there quickly will have the greatest deterrent impact. Slower-arriving conventional forces can be very effective at rolling back an adversary, but an aggressor may not believe they will actually be deployed in response to a fait accompli.

Nuclear weapons, of course, have the greatest capability to deny an attacker his objectives, but their use is heavily discounted by most adversaries involved in regional conflicts with conventional forces. However, a regime may feel a little less secure if it employs chemical or biological weapons—and the United States would do well to keep such adversaries guessing.

For adversaries willing to take high risks, deterrent threats may have to go beyond denial to punishment. In particular, the United States may wish to mount attacks on the military and internal security forces and other elements that help keep adversaries in power. Such attacks may urge more caution on regional powers.

How Broadly Can the United States Exercise a Deterrent Strategy?

As might be inferred from the above, there are ways the United States can enhance its deterrent posture. It can deploy forces forward or sustain the capability to project power rapidly in troubled regions. It can conduct frequent exercises aimed at demonstrating U.S. prompt denial capabilities. And it can retain an implicit nuclear option under some circumstances. All of these deterrence enhancements, however, are in tension with current basing, budgetary, and declaratory-policy trends. It thus appears that U.S. ability to deter risk-taking regimes may not extend much beyond a limited number of situations: those in which important U.S. interests are clearly at stake (e.g., Korea and the Persian Gulf) and perhaps a few others in which U.S. deterrent capabilities can dissuade an adversary from aggression.

This report is part of the RAND Corporation research brief series. RAND research briefs present policy-oriented summaries of individual published, peer-reviewed documents or of a body of published work.

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