For the past decade, Iran's nuclear program has been a proliferation concern to the United States. Given that Iran is awash with oil and gas reserves, Tehran's decision to allocate a major portion of its infrastructure investment to develop nuclear power plants has been puzzling. Until the spring of this year, the United States was practically alone in pressing for limits on Iranian access to nuclear weapons-related technology and materials. Western European states and Russia have differed with the United States in their assessment of the extent of Iran's nuclear program and its intentions to develop nuclear weapons. Europe, Russia, and Japan have also been reluctant to upset bilateral trade and political relations with Iran as a lever to prevent proliferation.