The United States Navy (USN) is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. It is the largest navy in the world, with a battle fleet tonnage that is greater than that of the next 13 largest navies combined. The U.S. Navy also has the world's largest carrier fleet, with 11 in service, one under construction (two planned), and one in reserve. The service has 321,053 personnel on active duty and 106,188 in the Navy Reserve. It operates 286 ships in active service and more than 3,700 aircraft.