Dec. 5 (UPI) -- Defense Secretary James Mattis extended the active-duty troop deployment on the U.S.-Mexico border to the end of January.
The deployment of about 5,600 U.S. troops to California, Arizona and Texas was set to expire Dec. 15, but Mattis, acting on a Department of Homeland Security request, extended it in an order Tuesday.
Most of the troops are unarmed and are working in support of civilian agencies including Homeland Security and Customs and Border Protection. Some troops have assisted agents in closing border crossings at Tijuana, Mexico.
Mattis said last week that most of the troops have completed the tasks for which they were sent to the border, including placing barbed wire, concrete barriers and other fortifications at border crossing points. He added that an extension of the mission will cost the military about $72 million, atop the $138 million spent prior to Dec. 15.
President Donald Trump ordered the placement of troops on the border prior to the midterm elections, as a caravan of migrants, largely from Honduras, approached the border.
The announcement of the extension did not specify how many troops would remain beyond Dec. 15, or if fresh troops would replace current troops.