The more than 5,200 active-duty troops being sent by President Donald Trump to the U.S.-Mexico border will be limited in what they can do under a federal law that restricts the military from engaging in law enforcement on American soil.
That means the troops will not be allowed to detain immigrants, seize drugs from smugglers or have any direct involvement in stopping a migrant caravan that is still about 1,000 miles from the nearest border crossing.
Instead, their role will largely mirror that of the existing National Guard troops — about 2,000 in all — deployed . . .