SC21 was a United States Navy program of the 1990s for new ship designs. The name comes from Surface Combatant and 21st Century. The main inital types were to be the DD21 and the CG21, though other ship types had concepts. In the late 1990s, the Arsenal ship was cancelled by Congress because having both the SC21 and AS were deemed to expensive. In the early 2000s Congress cut the SC21 budget by over half, resulting in a large reorganization of the program. A smaller tonnage DD(X) and CG(X) resulted. The program would be further cut in 2006, with the DD(X) being scaled back to two ships, and the CG(X) cancelled. The United States Navy (USN) is the branch of the United States armed forces responsible for conducting naval operations around the globe. ... The 1990s decade refers to the years from 1990 to 1999, inclusive. ... Future class of United States Navy destroyer. ... An arsenal ship is a ship which was proposed by the US Navy in 1996. ... The DD(X) with planned features. ... The CG(X) is a cruiser, the descendant of the DD(X) will replace the Ticonderoga-class AEGIS cruisers, with improved Missile Defense and Air Warfare capability. ...