Iran’s theocratic Shia regime has used its oil revenues to export the Islamic revolution and to fund an extensive nuclear weapons program. Yet Iran’s energy sector is also its greatest vulnerability, particularly its need to import gasoline to meet domestic demand. The most recent round of U.N. Security Council sanctions and unilateral sanctions by the European Union, Japan, and other countries offer some hope of stopping Iran’s nuclear program. The U.S. needs to aggressively enforce its own sanctions and lead efforts to persuade other countries to enforce existing sanctions and to impose their own sanctions.