For decades the United States and the European Union have collaborated to enhance European energy security. Their efforts have largely focused on addressing Europe’s high degree of reliance on imported Russian gas. Gazprom’s dominance has long enabled Moscow to engage in price gouging and politically motivated behavior. By focusing on diversifying Europe’s sources of supply and import routes for gas, as well as promoting the free flow of gas within the EU to eliminate “energy islands” in Central and Eastern Europe that have been highly dependent on Gazprom supplies, the US and the EU have driven down consumer costs and enabled many countries to regain their sovereignty. One of the most impressive examples of US-EU cooperation on energy security is their assistance to Ukraine to improve energy efficiency, reduce the demand for and diversify the supply of energy, and improve the transparency of its notoriously opaque and corrupt energy sector.