180420-M-OP674-043 PACIFIC OCEAN (April 20, 2018) Marines assigned to Maritime Raid Force (MRF), 31st Marine Expeditionary Unit (31st MEU), sit in an MH-60S Sea Hawk helicopter during visit, board, search, and seizure training during a certification exercise (CERTEX) aboard the Lewis and Clark-class dry cargo ship USNS Richard E. Byrd (T-AKE 4). MRF train regularly for quick, tactical raids of targets on both land and sea. CERTEX is the final evaluation in a series of training exercises which ensures readiness for crisis response throughout the Indo-Pacific region. (U.S. Marine Corps photo by Lance Cpl. Amy Phan/Released)