Pentagon sending additional 1,500 troops to southern border: US official

It was not immediately clear what specific units would be sent, though the Trump administration is expected to make a formal announcement later Wednesday.

The 1,500 additional service members will deploy to different locations along the southern border by the end of the month, the U.S. official said. 

The added troops will act in the same roles as the service members already there, providing aerial reconnaissance, data entry, training, vehicle maintenance, detection and monitoring, and some other logistical support roles. 

The announcement will mark the third time that U.S. troops have been sent to the southern border in the last two years.