美防长将视察美墨边界

Secretary of Defense Jim Mattis is due to visit the U.S. southern border Wednesday, where thousands of American troops have been deployed to support border patrol agents.

Speaking to reporters Tuesday at the Pentagon, Mattis said there has been “no change” to the U.S. military mission “at this time.”

"We're doing the obstacle emplacement, we do have helicopters down there,” he said. “We will have to see what the future holds, but right now that is the only mission I have.”

President Donald Trump called for increased border security to prevent a caravan of asylum-seeking migrants from Central America from entering the United States, declaring on several occasions its approach constituted a "national emergency."

More than 5,600 active duty troops and another 2,100 National Guard troops have moved into the U.S.-Mexico border area due to requests for help from the Department of Homeland Security.

A U.S. defense official told VOA Mattis will visit McAllen, Texas, where about 1,000 U.S. troops are deployed.

The U.S. troops assigned to help with border security are legally prohibited from engaging in domestic law enforcement, such as arresting migrants crossing the border.