U.S. Navy Senior Chief Damage Controlman Lawrence Lopez, right foreground, demonstrates how to remove a gas mask during damage control training aboard the amphibious assault ship USS Peleliu June 18, 2014, in the Pacific Ocean prior to Rim of the Pacific 2014. RIMPAC is a U.S. Pacific Command-hosted biennial multinational maritime exercise designed to foster and sustain international cooperation on the security of the world's oceans.