When its tanks rolled into Georgia, the Kremlin sent notice it intends to dominate the oil and natural gas resources of the former Soviet republics in the Caspian Sea basin, raising the threat of supply disruptions to Europe. That possibility could give Russia political leverage over Germany, the Czech Republic, Slovakia, Ukraine and other Central and East European countries that rely heavily on Russian fuels.

As rising oil prices strengthened the Kremlin’s hand, Mr. Putin clamped down on Russian businessmen, most notably by prosecuting and imprisoning Yukos Oil Co. Chief Executive Officer Mikhail Khodorkovsky.