200304-N-XL376-1082 GULF OF THAILAND (March 4, 2020) Sailors and 31st Marine Expeditionary Unit Marines embarked aboard the San Antonio-class amphibious transport dock ship USS Green Bay (LPD 20) participate in a mass casualty drill in support of Exercise Cobra Gold 2020, March 4, 2020. America Expeditionary Strike Group-31st Marine Expeditionary Unit is participating in Cobra Gold 20, the largest theater security cooperation exercise in the Indo-Pacific region and an integral part of the U.S. commitment to strengthen engagement in the region. (U.S. Navy photo by Mass Communication Specialist 3rd Class Maria G. Llanos/Released)