This report lists 234 instances in which the United States has used its armed forces abroad in situations of conflict or potential conflict or for other than normal peacetime purposes. It brings up to date a 1989 list that was compiled in part from various older lists and is intended primarily to provide a rough sketch survey of past U.S. military ventures abroad. A detailed description and analysis are not undertaken here.
The instances differ greatly in number of forces, purpose, extent of hostilities, and legal authorization. Five of the instances are declared wars: the War of 1812, the Mexican War of 1846, the Spanish American War of 1898, World War I declared in 1917, and World War II declared in 1941.
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 1950-53; the Vietnam War from 1964 to 1973; and the Persian Gulf War of 1991. In some cases, such as the Persian Gulf War against Iraq, Congress authorized the military action although it did not declare war.
The majority of the instances listed were brief Marine or Navy actions prior to World War II to protect U.S. citizens or promote U.S. interests. A number were actions against pirates or bandits. Some were events, such as the stationing of Marines at an Embassy or legation, which later were considered normal peacetime practice. 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 West.