"According to the Administration, Iran is a major national security challenge for the United States. The Administration perception is generated primarily by Iran's nuclear program but is compounded by Iran's military assistance to armed groups in Iraq and Afghanistan and to the Palestinian group Hamas and Lebanese Hezbollah. However, the threat assessment of some other governments was lessened by the December 3, 2007 key judgements of a National Intelligence Estimate (NIE) that indicates that Iran is likely not on a drive to develop an actual nuclear weapon. The Bush Administration argues that the NIE at least partly validates its approaches to containing the potential threat posed by Iran-strengthening international economic and political isolation of Iran to compel it to comply with international demands that it end its enrichment of uranium. Two U.N. resolutions (1737 and 1747) ban weapons of mass destruction (WMD)-related trade with Iran, freeze the assets of Iran's nuclear and related entities and personalities, prevent Iran from transferring arms outside Iran, and require reporting on international travel by named Iranians. With Iran still refusing to suspend enrichment, further sanctions remain under discussion at the U.N. Security Council, although the sanctions now under discussion appear to be more modest than those considered before the NIE was released. Separate U.S. efforts, showing some success, have included trying to persuade European governments to curb trade, investment, and credits to Iran; and pressuring foreign banks not to do business with Iran."
CRS Report for Congress, RL32048