Under the security dilemma, tensions and conflicts can arise between states even when they do not intend them. Some analysts have argued that the Cold War was a classic example of a security dilemma. This article disputes that notion. Although the Cold War contained elements of a deep security dilemma, it was not purely a case in which tensions and arms increased as each side defensively reacted to the other. The root of the conflict was a clash of social systems and of ideological preferences for ordering the world. Mutual security in those circumstances was largely unachievable. A true end to the Cold War was impossible until fundamental changes occurred in Soviet foreign policy.