Ten Virginia-class fast attack submarines are being built for the U.S. Navy by General Dynamics Electric Boat and its partner Newport News Shipbuilding.

The $17.6 billion order underscores the Navy's "commitment to an advanced and adaptable submarine force," Electric Boat said in announcing the award.

Virginia-class nuclear submarines are 377 feet long, 34 feet in diameter and displace 7,800 tons. They are capable of speeds of more than 25 knots and can dive to a depth of more than 800 feet with a full load of weaponry.

The ships carry Mark 48 advanced capability torpedoes, Tomahawk land-attack missiles and unmanned underwater vehicles.

The Navy already has 10 Virginia-class submarines with eight others under construction by the two companies. Work on the first submarine under this new order is scheduled to begin on Thursday.

"This award has great significance for the U.S. Navy, our company and the entire submarine industrial base," said Jeffrey S. Geiger, president of Electric Boat. "By continuing to produce two ships per year, the Navy and industry team retains the stability required to achieve increased efficiencies, providing the fleet with the submarines it needs to sustain the nation's undersea dominance."

"This is the largest number of boats ordered to date in a single contract block, which is great news -- particularly in light of today's challenging economic and political environments," said Newport News Shipbuilding President Matt Mulherin. "The Virginia-class program has already proven itself to be one of the best, if not the best, performing shipbuilding programs in the country and we look forward to continuing our important role in building these submarines."