181121-M-TC631-817 OTAY MESA, Calif. (Nov. 21, 2018) Marines assigned to 7th Engineer Support Battalion, Special Purpose Marine Air-Ground Task Force 7, attach concertina wire onto the California-Mexico border at the Otay Mesa Port of Entry in California, Nov. 21, 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 Sgt. Asia J. Sorenson/Released)