Under the United States Constitution, war powers are divided. Congress has the power to declare war, raise and support the armed forces, control the war funding (Article I, Section 8), and has "Power … to make all Laws which shall be necessary and proper for carrying into Execution … all other Powers vested by this Constitution in the Government of the United States, or in any Department or Officer thereof", while the President is commander-in-chief of the military (Article II, Section 2). It is generally agreed that the commander-in-chief role gives the President power to repel attacks against the United States and makes the President responsible for leading the armed forces. In addition and as with all acts of the Congress, the President has the right to sign or veto congressional acts, such as a declaration of war.
During the Korean and Vietnam wars, the United States found itself involved for many years in situations of intense conflict without a declaration of war. Many members of Congress became concerned with the erosion of congressional authority to decide when the United States should become involved in a war or the use of armed forces that might lead to war. The War Powers Resolution was passed by both the House of Representatives and Senate but was vetoed by President Richard Nixon. By a two-thirds vote in each house, Congress overrode the veto and enacted the joint resolution into law on November 7, 1973.
Presidents have submitted 130 reports to Congress as a result of the War Powers Resolution, although only one (the Mayagüez incident) cited Section 4(a)(1) and specifically stated that forces had been introduced into hostilities or imminent danger.
Congress invoked the War Powers Resolution in the Multinational Force in Lebanon Act (P.L. 98-119), which authorized the Marines to remain in Lebanon for 18 months during 1982 and 1983. In addition, the Authorization for Use of Military Force Against Iraq Resolution of 1991 (Pub.L. 102–1) which authorized United States combat operations against Iraqi forces during the 1991 Gulf War, stated that it constituted specific statutory authorization within the meaning of the War Powers Resolution.
On November 9, 1993, the House used a section of the War Powers Resolution to state that U.S. forces should be withdrawn from Somalia by March 31, 1994; Congress had already taken this action in appropriations legislation. More recently under President Clinton, war powers were at issue in former Yugoslavia; Bosnia; Kosovo; Iraq, and Haiti, and under President George W. Bush in responding to terrorist attacks against the U.S. after September 11, 2001. "[I]n 1999, President Clinton kept the bombing campaign in Kosovo going for more than two weeks after the 60-day deadline had passed. Even then, however, the Clinton legal team opined that its actions were consistent with the War Powers Resolution because Congress had approved a bill funding the operation, which they argued constituted implicit authorization. That theory was controversial because the War Powers Resolution specifically says that such funding does not constitute authorization." Clinton's actions in Kosovo were challenged by a member of Congress as a violation of the Wars Power Resolution in the D.C. Circuit case Campbell v. Clinton, but the court found the issue was a non-justiciable political question.
After the 1991 Gulf War, the use of force to obtain Iraqi compliance with United Nations resolutions, particularly through enforcement of Iraqi no-fly zones, remained a war powers issue. In October 2002 Congress enacted the Authorization for Use of Military Force Against Iraq Pub.L. 107–243 which authorized President George W. Bush to use force as necessary to defend the United States against Iraq and enforce relevant United Nations Security Council Resolutions.
May 20, 2011, marked the 60th day of US combat in Libya (as part of the UN resolution) but the deadline arrived without President Obama seeking specific authorization from the US Congress. President Obama, however, notified Congress that no authorization was needed, since the US leadership was transferred to NATO, and since US involvement is somewhat limited. On Friday, June 3, 2011, the US House of Representatives voted to rebuke President Obama for maintaining an American presence in the NATO operations in Libya, which they considered a violation of the War Powers Resolution.