WASHINGTON, March 4 (Reuters) - The U.S. Navy has replaced two ships it sent off the coast of Lebanon last week amid political deadlock there to send a signal to Syria, officials said on Tuesday. The cruiser USS Philippine Sea and the destroyer USS Ross replaced the destroyer USS Cole and a refueling ship over the past day, U.S. Navy officials said. Another refueling ship remained in place, meaning the United States continued to have three warships in the area, said the officials, speaking on condition of anonymity. The ships are not visible from the Lebanese coast but their presence...