Philippine Sea (June 18, 2006) - U.S. Navy aircraft carriers USS Kitty Hawk (CV 63), USS Abraham Lincoln (CVN 72) and USS Ronald Reagan (CVN 76) steam in formation to begin Exercise Valiant Shield 2006. Valiant Shield focuses on integrated joint training among U.S. military forces, enabling real-world proficiency in sustaining joint forces and in detecting, locating, tracking and engaging units at sea, in the air, on land and cyberspace in response to a range of mission areas. U.S. Navy photo by Chief Photographer's Mate Spike Call (RELEASED)