The end of the Cold War affected various regional conflicts differently. Some dormant conflicts erupted violently, while others, violent during the Cold War, moved toward peaceful resolution. The contrast between the Middle East peace process and the eruption of war in the Balkans in the 1990s illustrates these trends. During the Cold War, the Middle East was one of the more volatile war zones in the world. In contrast, during the same period the Balkans, a region famed for its instability before the two world wars, was relatively stable and peaceful. In the 1990s, the character of both regions changed: an Arab–Israeli peace process was under way, even if haltingly, while conflict and war returned to the Balkans (see chapter 6).

Why? How does a zone of war become more peaceful while a zone of peace becomes volatile and combustible in such a short time? Does this variation testify to the limitations of the global system's influence on regional developments? If a global change such as the end of the Cold War leads to more violence in some regions and to less violence in others, is this evidence that indigenous regional/domestic factors, rather than systemic ones, determine regional events? Here, then, is the puzzle: Regional variations under post-Cold War unipolarity may suggest that the structure of the international system is indeterminate with regard to regional outcomes, which are influenced more by nonsystemic characteristics.