"The Department of Defense (DOD) estimates that Congress has appropriated $1.6 trillion for war-related operational costs of the DOD since the terror attacks of September 11, 2001. When combined with an estimated $123.2 billion in related State Department and Foreign Operations appropriations, the DOD, Department of State (DOS), and U.S. Agency for International Development (USAID) have received an estimated $1.7trillion for activities and operations in support of U.S. response to the 9/11 attacks. Funding for these activities has been largely provided through supplemental appropriation acts or has been designated as an 'emergency' or 'Overseas Contingency Operation/Global War on Terror' (OCO/GWOT) requirement in annual agency budget requests -- or both. Funds designated as such are not subject to procedural limits on discretionary spending in congressional budget resolutions or to the statutory discretionary spending limits established by the Budget Control Act of 2011 (BCA). While there is no overall statutory limit on the amount of emergency or OCO/GWOT-designated spending, both Congress and the President have a fundamental role in determining how much OCO/GWOT and emergency spending is provided each fiscal year. Congress must designate any such funding as OCO/GWOT in statute on an account by account basis. The President is also required to designate it as such after it is appropriated in order for it to be available for expenditure."
CRS Report for Congress, R44519
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html