There appears to be a growing international consensus to adopt progressively strict economic sanctions against Iran to try to compel it to compromise on its further nuclear development. The U.S. view - increasingly shared by major allies-is that sanctions should target Iran's energy sector, which provides about 80% of government revenues, and try to isolate Iran from the international financial system. U.S. efforts to curb international energy investment in Iran's energy sector began in 1996 with the Iran Sanctions Act (ISA). ISA has been expanded significantly in 2010. This report discusses said expansions, provides background on the ISA, and explores how this Act has affected