FILE PHOTO: A U.S. Marine stands guard, behind a barricade with concertina wire, at the border between Mexico and the U.S., in preparation for the arrival of migrants, in Tijuana, Mexico November 13, 2018. REUTERS/Jorge Duenes

WASHINGTON (Reuters) - The U.S. military said on Monday it would send about 320 Defense Department personnel to the border with Mexico in roles that would increasingly put them in contact with migrants, including driving them in vehicles and “monitoring” their welfare.

The Pentagon’s statement said the latest deployment would alone cost about $7.4 million through September and broadly confirmed details of the deployment previewed on Friday

The U.S. military deployments at the border, which now include about 5,000 forces, are being closely watched by proponents and foes of President Donald Trump’s politically charged immigration policies.