Updated at 7:25 p.m. ET
The Department of Homeland Security has asked several federal agencies to send civilian law enforcement officers to the border, according to a DHS official. These agencies include the Departments of State, Justice, Energy, Transportation, Labor and Interior, the DHS official said, speaking on the condition of anonymity.
"The President has made it clear that border security is a top administration priority," DHS spokeswoman Katie Waldman said in a statement. "In line with the President's direction and given the very real threat we face at the border from potential mass migration actions – of course, DHS has reached out for assistance from partners across the federal government to defend our sovereignty, protect our frontline men and women, and secure our border. We appreciate all of the support we have received to date."
The request comes as Defense Secretary Jim Mattis is expected to extend the deployment of thousands of U.S. active-duty troops at the Mexico border through the end of January, Pentagon officials tell NPR. The deployment had been slated to end on Dec. 15.
In addition to moving the withdrawal date back, the defense chief is also likely to reduce the force's size to around 4,000 personnel, from the current number of about 5,900.
Mattis is expected to sign the Department of Homeland Security's request for assistance at the border this weekend, when the news is expected to be formally announced.
Some troops will go home under the plan, with new troops deployed to replace them. But others will remain through the holiday season. Senior officers and their staff are working now to determine which units will be withdrawn.
In cases where units are based nearby, such as at Camp Pendleton, they might be given short-term passes to visit their families for Christmas, officials tell NPR.
The active-duty military personnel who have been deployed to the U.S.-Mexico border are meant to provide only a supporting role to Customs and Border Protection agents, mainly in logistical help — everything from installing barbed wire to moving personnel — as part of the Trump administration's response to the arrival of thousands of migrants from Central America who have traveled to the U.S. in a large caravan.
The deployed troops have included military engineers and military police; officials say medical and aircraft units are also needed to bolster the U.S. presence at its Southern border.
So far, a key job for the troops has been to install roll after roll of concertina wire along the border. Some of the engineering teams who were involved in that effort will now go home — and won't be replaced — because their work is done, defense officials say.
In addition to the active-duty personnel, the Trump administration has sent 2,100 National Guard troops to the border.
The unusual decision to send active-duty troops to the Mexico border, rather than deploying only National Guard personnel, has sparked a wide range of reactions, from criticism to praise.
As we reported earlier this week, "Trump's political opponents called the move, which came just before the November midterm elections, an overreaction — and even a stunt."