Instances of Use of United States Armed Forces Abroad, 1798-2015

CONGRESSIONAL RESEARCH SERVICE - January 15, 2015

Barbara Salazar Torreon 
Analyst in Defense Budget and Military Manpower

SUMMARY:
This report lists hundreds of instances in which the United States has used its Armed Forces  abroad in situations of military conflict or potential conflict or for other than normal peacetime  purposes. It was compiled in part from various older lists and is intended primarily to provide a  rough survey of past U.S. military ventures abroad, without reference to the magnitude of the  given instance noted. The listing often contains references, especially from 1980 forward, to  continuing military deployments, especially U.S. military participation in multinational  operations associated with NATO or the United Nations. Most of these post-1980 instances are  summaries based on presidential reports to Congress related to the War Powers Resolution. A  comprehensive commentary regarding any of the instances listed is not undertaken here.  The instances differ greatly in number of forces, purpose, extent of hostilities, and legal  authorization. Eleven times in its history the United States has formally declared war against  foreign nations. These 11 U.S. war declarations encompassed 5 separate wars: the war with Great  Britain declared in 1812; the war with Mexico declared in 1846; the war with Spain declared in  1898; the First World War, during which the United States declared war with Germany and with  Austria-Hungary during 1917; and World War II, dur ing which the United States declared war  against Japan, Germany, and Italy in 1941, and agai nst Bulgaria, Hungary, and Rumania in 1942.   Some of the instances were extended military engagements that might be considered undeclared  wars. These include the Undeclared Naval War with France from 1798 to 1800; the First Barbary  War from 1801 to 1805; the Second Barbary War of 1815; the Korean War of 1950-1953; the  Vietnam War from 1964 to 1973; the Persian Gulf War of 1991; global actions against foreign  terrorists after the September 11, 2001, attacks on the United States; and the war with Iraq in  2003. With the exception of the Korean War, all of these conflicts received congressional  authorization in some form short of a formal declaration of war. Other, more recent instances  often involve deployment of U.S. military forces as part of a multinational operation associated  with NATO or the United Nations.  The majority of the instances listed prior to World War II were brief Marine or Navy actions to  protect U.S. citizens or promote U.S. interests.  A number were actions against pirates or bandits.  Covert actions, disaster relief, and routine alliance stationing and training exercises are not  included here, nor are the Civil and Revolutionary Wars and the continual use of U.S. military  units in the exploration, settlement, and pacification of the western part of the United States.   For additional information, see CRS Report RL31133,  Declarations of War and Authorizations  for the Use of Military Force: Historical Background and Legal Implications , by Jennifer K.  Elsea and Matthew C. Weed and CRS Report R41989,  Congressional Authority to Limit Military  Operations , by Jennifer K. Elsea, Michael John Garcia, and Thomas J. Nicola.

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