Authorization for Use of Military Force Against Terrorists

The Authorization for Use of Military Force allows the use of United States Armed Forces against those responsible for the attacks on September 11, 2001. 
The authorization granted the President the authority to use all "necessary and appropriate force" against those whom he determined "planned, authorized, committed or aided" the September 11th attacks, or who harbored said persons or groups. The AUMF was signed by President George W. Bush on September 18, 2001.