General Dynamics Corp. has been awarded a $22.2 billion contract from the U.S. Navy to build nine more nuclear-powered Virginia-class submarines, the largest shipbuilding contract in the service’s history. The contract includes an option for a 10th vessel over five years. The Virginia-class submarines are designed to attack both land and sea targets with Tomahawk cruise missiles and other weapons. Eighteen of the attack submarines have been delivered to date, including $17 billion for the prior installment.