The admiral who leads U.S. military forces in Latin America will step down at the end of this year, Defense Secretary Pete Hegseth announced on Thursday, in a surprise move amid escalating tensions with Venezuela.

Alvin Holsey took over the U.S. military’s Southern Command late last year for a position that normally lasts three years. A source familiar with the matter told Reuters that there had been tension between him and Hegseth and questions about whether he would be fired in the days leading up to the announcement.

Hegseth, in his social media post, did not disclose the reason for the departure of Holsey, who is one of only two Black four-star officers leading a U.S. combatant command.