A top adviser to Defense Secretary Pete Hegseth has left his position, the Pentagon announced late Saturday, becoming the latest in a string of senior officials to leave the department’s top ranks.

The official, Justin Fulcher, joined the Trump administration as part of the Department of Government Efficiency, Elon Musk’s government overhaul initiative, and later became an adviser to Mr. Hegseth.

In a statement, Mr. Fulcher said he had planned to work for the federal government for only six months.

Earlier this month, The Washington Post detailed a confrontation between Mr. Fulcher and other DOGE staff members assigned to the Pentagon. But officials downplayed that incident as a cause, insisting Mr. Fulcher’s exit was friendly.