In his first trip as Pentagon chief, Hegseth will survey operations and meet with US troops, which have been surged to the region under Trump.

"Looking forward to meeting our great warriors and seeing the hard work they are doing securing our southern border. We will continue to deliver on this vital mission," Hegseth wrote on X in a post announcing his arrival.

Trump ordered 1,500 additional military personnel to the border just days after taking office, and his administration has carried out highly publicized immigration raids and arrests. Some migrants have additionally been deported using military aircraft.

Border security is a key priority for the president, who declared a national emergency at the US frontier with Mexico on his first day in office.

The additional personnel have increased the total number of active-duty troops deployed there to around 4,000.

Ahead of his border visit, Hegseth posted on X that Trump "wants 100% operational control of the border -- and we will deliver."

"BORDER SECURITY IS NATIONAL SECURITY," Hegseth wrote.