Two days after President Donald Trump took the oath of office, active-duty U.S. military troops are preparing to head to the southern border.

The Pentagon is sending at least 1,500 active-duty troops to the southern border to enhance security and assist with a major military airlift of undocumented migrants.

The president has directed the U.S. military to reinforce the border, and the acting secretary of defense on Wednesday announced the Pentagon is sending around 1,500 active duty troops to the country’s southern border, joining 2,500 active duty personnel already there.

A U.S. Border Patrol agent killed during a traffic stop near the Canadian border worked security duty at the Pentagon during the time of the Sept. 11 attacks.

The I Marine Expeditionary Force is made up of about 53,000 active-duty troops, who are primarily stationed at Camp Pendleton, as well as at Marine Corps Air Stations Miramar and Yuma, and the Marine Corps Air/Ground Combat Center at 29 Palms, California.

The move enacts President Trump's executive orders issued shortly after he took office to intensify immigration enforcement.

The deployment signals the military’s increased role in a much more aggressive immigration policy under the second Trump administration.

Acting Defence Secretary Robert Salesses said the Pentagon will provide military aircraft to support Department of Homeland Security deportation flights for more than 5,000 detained migrants and the troops will assist in the construction of barriers.