With every passing hour, Ukraine seems to move closer to the brink of disaster. The causes are multifaceted, but a key driver of the crisis has been Ukrainian — and European — dependence on Russian natural gas. In the short term, U.S. officials are understandably scrambling to keep events from spiraling out of control in Crimea, where Russian troops have taken control of much of the peninsula. In the long term, however, the United States may be able to tip the balance against President Vladimir Putin, using the American shale-gas boom to weaken Russia’s geopolitical leverage in Ukraine.Â