Defense Secretary Mark Esper has approved a request for assistance from the Department of Homeland Security that would authorize the deployment of 4,000 U.S. military personnel at the southern border beginning in October, with more of the force coming from the National Guard.
"The duties to be performed by military personnel include the same categories of support as those currently being carried out along the border, including detection and monitoring, logistics, and transportation support to U.S. Customs and Border Protection," according to a statement from Pentagon spokesman Lt. Col. Chris Mitchell.
"Military personnel will not directly participate in civilian law enforcement activities," he said.
The U.S. military mission on the southern border has been criticized and opposed by Democrats, but the Pentagon says troops will assist DHS there for as long as President Trump orders it.
Trump declared an emergency at the border last year and has diverted billions of dollars from the Pentagon to build a wall between Mexico and the United States. The funding shifts, meanwhile, have drawn opposition from Democrats and Republicans alike.