Two nuclear-capable Soviet warships and an oiler will dock July 21 at Atlantic Fleet headquarters in Norfolk, Va., marking the first time Soviet warships have visited a U.S. military port, the Navy said. The four-day visit by a Soviet destroyer and cruiser, both capable of firing nuclear-tipped cruise missiles, is part of a good-will exchange agreement in which U.S. warships will later visit a Soviet port. The schedule and details of the American visit were still being discussed, a Navy spokesman said. Arriving aboard the Soviet warships will be a small number of civilians and 1,100 Soviet naval personnel. The visiting ships will include the Slava-class guided-missile cruiser Marshal Ustinov and the Sovremenny-class destroyer Otlichnny.