Strategic sealift ships are part of the United States Military Sealift Command's (MSC) prepositioning program. There are currently 49 located in the Indian Ocean at Diego Garcia and the Western Pacific Ocean at Guam and Saipan.
The MPS ships in each squadron have sufficient equipment, supplies and ammunition to support a Marine Air-Ground Task Force for 30 days. The MPS ships are self-sustaining, with cranes to unload at sea or pierside. MSC chartered the first two ship classes in the MPS role (the Corporal Louis J. Hauge Jr. and Sergeant Matej Kocak classes) from civilian shipping lines and converted them. Later ships were purpose-built.
The Sergeant Matej Kocak Class, the second class of MPS ships chartered by MSC, also gained 157 feet (48 m) amidships and a helicopter deck after conversion. These ships, delivered to MSC in the mid-1980s, built at Sun Shipbuilding & Drydock Co., Chester, Pennsylvania and converted at National Steel and Shipbuilding Company, San Diego. They were previously owned by Waterman Steamship Corporation but recently sold to MSC and now operated by Keystone Shipping Co.