"The Bush Administration has pursued several avenues to attempt to contain or end the potential threat posed by Iran, at times pursuing limited engagement directly or through allies, and at other times leaning toward pursuing efforts to change Iran's regime. A potential international crisis has loomed over Iran's nuclear program after a U.S.-supported effort by three European nations to limit Iran's nuclear program broke down in August 2005. International concerns on nuclear issues and other strategic issues have been heightened by the accession of Mahmoud Ahmadinejad, a hardliner, as president of Iran. He consistently advocated a return to many of the original principles of the Islamic revolution as set down by the late Ayatollah Ruhollah Khomeini. Some advocate military action against Iran's nuclear infrastructure, but others believe that continued diplomacy, combined with offers of economic rewards or threats of punishment, is the only viable option. Still others believe that only an outright replacement of Iran's regime would diminish the threat posed by Iran to U.S. interests. U.S. sanctions currently in effect ban or strictly limit U.S. trade, aid, and investment in Iran and penalize foreign firms that invest in Iran's energy sector, but unilateral U.S. sanctions do not appear to have materially slowed Iran's WMD programs or shaken the regimes grip on power."
CRS Report for Congress, RL32048