In the United States, "Merchant Marine" has a different meaning. The United States Merchant Marine (USMM) is a part of the military which is controlled by the government in both peace and war. When the United States is at war, the USMM is used to carry military supplies. In World War II, nearly one out of every twenty-six American merchant mariners was killed, a higher portion of men than in the Army, Navy, or even the Marines.