GROTON, Conn. (AP) — The Navy has announced a proposed $9.5 billion contract with General Dynamics’ Electric Boat to build the first two submarines of a new generation of ballistic missile vessels.

The new Columbia-class submarines are being built at Electric Boat’s shipyards in Groton, Connecticut, and Quonset Point, Rhode Island.

Early construction began at Quonset Point in 2017. Final assembly is set to begin in 2024 in Groton.

The contract announced Monday requires congressional approval.

The Navy also said it will be giving Electric Boat another $869 million to continue design and engineering of the submarines, and efforts to expand the submarine industrial base.