Military Sealift Command (MSC)

Organization of the U.S. Navy that controls most of its resupply and transport ships. The Military Sealift Command (MSC) was founded in 1949 and grew out of the Military Sea Transportation Service (it acquired its present name in 1970). The part of the MSC most directly associated with supporting the navy is the Naval Fleet Auxiliary. A counterpart of the U.S. MSC is the Royal Fleet Auxiliary of Great Britain.

During a war, more than 95% of all equipment, fuel, supplies, and ammunition needed to maintain the military are carried by sea. The Vietnam War marked the last time that troops were transported by MSC troop ships. Since Vietnam, most troops have been transported by air.

Ships of the MSC are run by civilians and are formally in service, as opposed to being in commission. The distinction is important because the term commission implies the conferring of military rank or authority. The hull numbers of MSC ships begin with the prefix T-, followed by the hull number that a ship of the same type, commissioned by the U.S. Navy, would have. Some ships operated by the MSC are owned by the U.S. government, whereas others are chartered. Those owned by the government bear the prefix USNS (which stands for United States Naval Ship).