181126-M-YE163-1076 SAN YSIDRO, Calif. (Nov. 26, 2018) Marines with 7th Engineer Support Battalion, Special Purpose Marine Air-Ground Task Force 7, install concertina wire near the San Ysidro Port of Entry in California while assisting U.S. Customs and Border Protection at the U.S. and Mexico border, Nov. 26, 2018. U.S. Northern Command is providing military support to the Department of Homeland Security and U.S. Customs and Border Protection to secure the Southern border of the United States. (U.S. Marine Corps photo by Staff Sgt. Rubin J. Tan/Released)