PACIFIC OCEAN (Sept. 19, 2020) USS Chicago (SSN 721) conducts a battle damage assessment of the decommissioned frigate USS Curtis (FFG 38) during a sinking exercise (SINKEX) as part of Valiant Shield 2020. Valiant Shield is a U.S. only, biennial field training exercise (FTX) with a focus on integration of joint training in a blue-water environment among U.S. forces. This training enables real-world proficiency in sustaining joint forces through detecting, locating, tracking, and engaging units at sea, in the air, on land, and in cyberspace in response to a range of mission areas. (U.S. Navy photo courtesy of USS Chicago)