Border troops cannot engage in law enforcement

PHOENIX (AP) — 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 to the border over the last six months, including providing helicopter support for border missions, installing concrete barriers and repairing and maintaining vehicles. The new troops will include military police, combat engineers and helicopter companies equipped with advanced technology to help detect people at night.

The extraordinary military operation comes a week before the November 6 mid-term elections as Trump has sought to transform fears about the caravan and immigration into electoral gains. On Tuesday, he stepped up his dire warnings, calling the band of migrants fleeing poverty and violence in Central America an "invasion."