The opening of the Caspian Sea basin to Western investment following the breakup of the Soviet Union produced a major contest for access to the region's vast energy reserves on the part of powers as close as Russia, Turkey, and Iran, and as far away as Japan and the United States. Indeed, the struggle to exploit Caspian oil has been one of the most monumental geopolitical developments of the post-Cold War era as external powers vie for political, economic, and military influence in a region brimming not only with oil, but also with ethnic conflicts and historical animosities.

The coming...