Report: Extended Deterrence and Security in East Asia


In view of their centrality to the Cold War U.S.-Soviet relationship, deterrence and extended deterrence are inevitably loaded terms, weighted down by history. With this in mind, applying the logic of extended deterrence in modern-day East Asia requires special care to avoid some of its assumptions; it should be clear, for example, that China is not the Soviet Union and that America’s relationship with twenty-first-century China is fundamentally different from its relationship with the U.S.S.R. Despite this, however, close scrutiny of the Cold War experience may provide useful lessons—including in the differences between today’s world and the past. Notwithstanding those differences, extended deterrence remains a useful analytical framework in assessing security and stability in East Asia and a helpful language in conversations between the United States, Japan, and South Korea.

Deterrence generally refers to the ability to discourage an attack through the threat of retaliation, while extended deterrence describes deterrence on behalf of a third party, typically an ally. During the Cold War, analysts often defined deterrence and extended deterrence largely or even strictly in nuclear terms; for example, John Lewis Gaddis described extended deterrence as the threat of “a nuclear-strategic response in case of a nuclear attack on the territory or troops of allies.”1 As the danger of strategic nuclear war has receded since the Soviet Union’s collapse, many definitions of deterrence and extended deterrence have widened to include conventional military threats. Taking into account that political and economic considerations also substantially shape twenty-first-century decision making on war and peace, it may now be appropriate to view deterrence in an even broader context.

Closely related to extended deterrence is assurance, the ability to encourage the third party that deterrence on that nation’s behalf is in fact effective and reliable. The distinction between extended deterrence and assurance is a critical one since each is fundamentally psychological and subjective. Thus the United States could succeed in deterring a potential adversary yet fail in assuring an ally or, conversely, succeed in assurance but fail in deterrence. U.S. officials might believe that deterrence and assurance are succeeding when its rivals or partners do not. Like beauty, successful deterrence and assurance lie in the eye of the beholder.

Discussion during the two dialogue meetings repeatedly demonstrated the critical importance of understanding the psychological aspects of deterrence. One South Korean participant stated this simply, saying that successful deterrence “rests on attacking the mind rather than the body.” Recognizing that deterrence succeeds or fails in the minds of those whom one seeks to deter, participants asked frequently whether the United States and its allies are creating the proper incentives and how these incentives are understood. In other words, are our deterrence efforts credible and are they evaluated through rational and pragmatic decision-making processes? Each question proved to be a source of concern for some.

Equally fundamentally, participants considered many important questions about the goals of deterrence and extended deterrence in East Asia. Whom do the United States and its allies seek to deter? What are the limits of deterrence? Is deterrence strictly a military security concept or does the logic of deterrence apply in other areas as well? Is there such a thing as “too much” deterrence? The answers can profoundly shape U.S. policy in a critical region.


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