U.S. Navy photo by Petty Officer 3rd Class Aaron Ainley, left, explains the functions of the DNS-300 underwater sonar system to South Korean navy SEALs during Exercise Clear Horizon 2015 on Commander Fleet Activities Chinhae, South Korea, Nov. 5, 2015. Ainley is an explosive ordnance disposal technician assigned to Mobile Unit 1. The annual exercise between the U.S. and South Korean navies focuses on increasing capabilities between ships, and on mine countermeasures in international waters surrounding the Korean peninsula. U.S. Navy photo by Petty Officer 2nd Class Daniel Rolston