The U.S. Navy awarded General Dynamics NASSCO a $156.6 million contract for shipyard work on the USS Essex, a large amphibious assault ship that joined the fleet in the 1990s.

The Essex is a Wasp-class ship whose large, flat deck gives it the appearance of an aircraft carrier. It can carry a maximum of 1,871 U.S. Marines as well as aircraft and vessels to get them ashore.

The work program for the ship is called a phased maintenance availability. It will upgrade the ship’s military and technical capabilities. Work is expected to be complete by June 2017.

The Southwest Regional Maintenance Center in San Diego awarded the contract modification, which the Navy announced March 1.

General Dynamics stock trades on the New York Stock Exchange under the symbol GD. The NASSCO shipyard also builds ships.