Recent moves and countermoves by the U.S. and Iran in the Persian Gulf over the past few months have increased speculation about the prospect of war in the region. Some members of Congress, including a few Republicans, have stated that the president cannot use military force against the Islamic Republic without the approval of the legislature.
In the aftermath of the September 11th attacks, Congress voted to authorize military force against against those who had “planned, authorized, committed, or aided the terrorist attacks” or who "harbored such organizations or persons, in order to prevent any future acts of international terrorism against the United States. . . ." More than a decade later, the United States continues to conduct military operations against Al Qaeda and affiliated groups—including, somewhat surprisingly, against the Islamic State—pursuant to this 2001 authorization. In the spring of 2015, despite claiming that a new AUMF for airstrikes and limited operations in Syria and Iraq was not legally required, the Obama Administration presented draft language to Congress for a new AUMF. Riven by disagreements over details, Congress has thus far refused to support the President’s proposal.