The Pentagon has extended its assistance to the Department of Homeland Security along the southern border until September, according to a Defense Department statement. Acting Secretary of Defense Pat Shanahan approved DOD assistance through Sept. 30, and the department will be “transitioning its support at the southwestern border from hardening ports of entry to mobile surveillance & detection.” Along with the surveillance, the department said it would be installing “concertina wire” between ports of entry and would continue to provide aviation support. The mission had already been extended once until Jan. 31. According to the Marine Corps Times, there are now about 4,500 active duty troops and National Guard forces currently on the border. They were first sent there after President Donald Trump requested the military presence to bolster existing law enforcement along the Mexico border.