The Department of Defense awarded General Dynamics' (NYSE: GD) National Steel and Shipbuilding Company subsidiary, or NASSCO, a "not-to-exceed" $11.2 million contract modification Monday, hiring NASSCO to draw up detailed designs for Afloat Forward Staging Base, or AFSB, modifications to the U.S. Mobile Landing Platform vessels MLP 3 and MLP 4.

NASSCO built the Navy's first MLP, the USNS Montford Point -- MLP-1 -- and recently delivered it to the Navy. The company is now in the process of building MLP-2, which is scheduled for delivery in Q1 2014, and MLP-3, on which it began work in February.

MLP-3 and MLP-4 are both expected to be designed as AFSBs, an MLP variant that will feature an enlarged flight deck for operating helicopters and tilt-rotor aircraft on special operations and mine-sweeping missions.

NASSCO's design work on the new variants contract should be complete by November.