US policy has tried to blunt Iranian adventurism for several decades through international diplomacy and economic sanctions. International cooperation with US initiatives have been modest, and extensive US unilateral sanctions against Iran—codified in the Iran and Libya Sanctions Act of 1996—have not achieved their difficult goals. Despite this checkered past, some US political leaders are now calling for broader economic and/or military responses to the ongoing Iranian nuclear program and support for Hezbollah. In formulating the appropriate US response to these outrages, the Congress should reflect on our past sanctions experience as well as the new diplomatic and economic conditions that will constrain the effectiveness of new US and multilateral measures.