The military uses ships to move supplies and people and to project power around the world. Here's a look at who has these vessels and what they're used for.
U.S. Navy
The Navy has around 430 commissioned ships of all types, from aircraft carriers and destroyers to submarines and amphibious warfare ships.
All aircraft carriers and submarines are nuclear powered. Submarines also carry nuclear weapons and constitute one leg of the nuclear triad — the other components being bombers and intercontinental ballistic missiles.
The oldest Navy ship is the USS Constitution, also known as "Old Ironsides," a three-masted heavy frigate launched in 1794. About 60 sailors man the ship, which is used for ceremonial and special events and education tours.
The Military Sealift Command has about 130 noncommissioned ships, mostly used to transport munitions, equipment, fuel and supplies for the military, wherever needed. The ships are owned by the Navy, but manned mostly by civilians, not Navy sailors.
U.S. Army
The Army has its own fleet of ships, including landing craft, tugs, barges, dredges, logistic support vessels and even aircraft repair ships.
The General Frank S. Besson-class logistic support vessels are the Army’s largest ships at 273 feet long. They can even haul heavy Abrams main battle tanks. Soldiers who man these vessels like to be referred to as Army mariners, not sailors.
U.S. Air Force
The Air Force has the fewest number of ships among the services — just two: the 71-foot-long Rising Star, a tugboat based at Thule Air Base, Greenland, and the 120-foot 82nd Aerial Targets Squadron drone recovery watercraft. Like all of the services, the Air Force has a fleet of small boats not referred to as ships, including patrol craft and inflatables.
U.S. Coast Guard
The Coast Guard has a fleet of ships that it refers to collectively as cutters. To qualify as a cutter, the vessel has to be 65 feet or greater in length; otherwise, it’s a boat.
The longest cutter is the USCGC Healy, a 420-foot icebreaker. The shortest cutters are the 65-foot inland and river buoy tenders and small harbor tugs.