US Defence Secretary Pete Hegseth has dismissed Army Lt Gen Brett Sylvia, the Pentagon’s top military planner, leaving a key strategic position vacant as President Donald Trump weighs fresh military strikes against Iran. The Atlantic first reported the move. Officials have not publicly explained the decision.

Sylvia served as director of Strategy, Plans and Policy on the Joint Staff, commonly known as the J5. He developed military strategies, contingency plans and operational options for senior military leaders, including Joint Chiefs of Staff Chairman General Dan Caine.

A defence official, speaking anonymously, said the Pentagon had not immediately named a permanent replacement. Sylvia’s official military biography was also removed shortly after his dismissal.

A Joint Staff spokesperson thanked Sylvia and his family for his 32 years of military service.

“The Chairman, the Joint Staff, and the Joint Force extend our deepest gratitude to Lt. Gen. Brett Sylvia and his family for their 32 years of distinguished service to our nation,” the spokesperson said, adding that they wished the family well in their future endeavours.

Sylvia’s departure comes as US Central Command (Centcom) prepares updated military options for possible strikes against Iranian military targets and regional infrastructure.

The J5 does not directly command troops during combat. However, it coordinates military plans with broader US strategic priorities. Its responsibilities include assessing operational needs, logistical challenges, global military commitments and diplomatic considerations.

Sylvia is reportedly the second lieutenant general to leave the J5 position within a year. His predecessor, Lt Gen Joseph McGee, was forced to retire in October 2025, according to the report. Maj Gen Mark Slocum, the directorate’s vice director, is reportedly overseeing its work on an interim basis.

Sylvia’s dismissal is the latest in a series of senior military leadership changes under Hegseth. According to the report, nearly two dozen senior officers, including generals, admirals and service branch leaders, have been dismissed or pushed into early retirement without public explanations for their individual departures.

Hegseth has defended the changes as an effort to reduce bureaucracy and strengthen accountability across the armed forces.

'I directed that we reduce the overall number of general officer slots,' Hegseth told junior officers at Marine Corps Base Quantico. 'The media calls that a purge. I call it accountability and long overdue, and frankly, the bare minimum.'

The Pentagon aims to reduce the total number of general officer positions by 20 per cent by January 1, 2027. It has not given a specific reason for Sylvia’s removal.

The dismissals have drawn criticism from lawmakers, including former military personnel serving in Congress. Critics warn that removing experienced senior officers could weaken military planning amid rising international tensions.

Senator Mark Kelly, an Arizona Democrat, former Navy combat pilot and astronaut, criticised the changes.

“He's purging a generation of great leaders of the military, and it's going to take a generation to recover from it,” Kelly said. “He's got some kind of deep-seated grievance about leadership in the military.”