U.S. Navy and Japan Maritime Self-Defense Force ships are underway in formation. U.S. Navy and Japan Maritime Self-Defense Force ships are underway in formation during Keen Sword 2011 in the Philippine Sea on Dec. 10, 2010. Keen Sword is a bilateral exercise designed to strengthen maritime capabilities between the U.S. and Japan. SHARE: Download: Full Size (0.04 MB) Credit: VIRIN: 248816-N-VFJ95-051.jpg Photo Gallery