(WASHINGTON) -- As a caravan of migrants makes its way through Mexico towards the United States, Defense Secretary James Mattis is expected to sign an order Thursday that would deploy hundreds of active duty troops to the southern border, according to a U.S. official.
The initial estimate is that 800 to 1,000 service members could deploy in logistical support of Customs and Border Patrol, such as setting up tents for border authorities, the official said. Among their potential tasks, they would also be helping in the construction of fencing that is separate from the border wall.
These active duty forces will not act in a law enforcement capacity, but strictly providing logistical support to CBP and therefore not covered by the Posse Comitatus Act that prohibits the use of active duty forces in a law enforcement capacity.
There are already about 2,000 National Guard troops called up by the governors of Arizona, New Mexico, and Texas to support the Trump administration's border security mission.
Like Guard troops already activated along the border, these new active-duty troops will not be engaging with migrants, but, like the Guard, they will also retain the right to self-defense, the official said.
The active-duty troops are expected to provide additional support in a much more visible way than their National Guard counterparts, the official added.
Speaking at a rally in Wisconsin on Wednesday night, President Trump hinted at the use of the U.S. military in an additional role on the southern border.
"But wait until you see what happens over the next couple of weeks," Trump said. "You're going to see a very secure border. You just watch. Just watch. Very secure. And the military is ready. They're all set. They're all set."
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