U.S Air Force Staff Sgt. Justin Browning, 917 Maintenance Squadron crew chief, works with U.S. Air Force Maj. Maury Kent prior to a sortie during Rim of the Pacific exercise at Joint Base Pearl Harbor-Hickam, Hawaii, July 17,2012. Twenty-two nations, more than 40 ships and submarines, more than 200 aircraft and 25,000 personnel are participating in RIMPAC exercise from June 29 to Aug. 3, in and around the Hawaiian Islands. The world's largest international maritime exercise, RIMPAC provides a unique training opportunity that helps participants foster and sustain the cooperative relationships that are critical to ensuring the safety of sea lanes and security on the world's oceans. RIMPAC 2012 is the 23rd exercise in the series that began in 1971.