In an exhaustive analysis of Soviet documents, the author argues that the deterrence theory that underlay American policy in the Third World and led to involvements in Korea, Vietnam, and elsewhere during the Cold War was not borne out by changes in Soviet thinking. That is, U.S. military intervention and other tough policies did not deter the Soviets, while other instruments such as diplomacy were more effective in provoking cooperative behavior. Excessive attention to Soviet words rather than deeds flaws the author's major conclusions. Collapse of the American position in Indochina was in fact followed by an upsurge in support for radical Third World clients, while the Reagan doctrine brought about a retrenchment of Soviet Third World commitments. However, the author raises an important issue: deterrence is much more complicated than simple models suggest. Failure to meet a commitment in a peripheral area does not necessarily undermine deterrence with respect to core interests, while reputations for softness and the reverse may be more easily won and lost than leaders think. All of this suggests the need for a more segmented view of how deterrence actually works.