The Pentagon placed a top adviser to Defense Secretary Pete Hegseth under administrative leave Tuesday after a probe into potential leaks of sensitive information, according to a defense official.

Dan Caldwell was escorted out of the Pentagon by security officers and had his building access suspended pending further investigation, according to the official, who was granted anonymity to discuss an ongoing investigation.

His suspension comes as the Trump administration seeks to root out leaks, including at the Defense Department. A March memo signed by Hegseth’s chief of staff asked the Pentagon’s director for defense intelligence to look into unauthorized disclosures and approved the use of polygraphs.

Reuters first reported Caldwell’s removal.

Caldwell, a Marine Corps veteran of the Iraq War who previously worked at the right-leaning Defense Priorities think tank, had a key role in advising the Pentagon on Ukraine.

Hegseth — in the now now infamous Signal chat with national security leaders that accidentally included a journalist — named Caldwell the Pentagon’s primary contact to coordinate U.S. military strikes on Yemen.

Caldwell did not immediately respond to a request for comment.