A senior advisor to Department of Defense Secretary Pete Hegseth was escorted out of the Pentagon and placed on administrative leave, according to a Defense Department official.

Dan Caldwell was suspended over an “unauthorized disclosure” of information amid an ongoing investigation into leaks from within the Pentagon. Caldwell, a foreign policy realist, previously worked with the restraint-oriented think tank Defense Priorities and Concerned Veterans for America, which was formerly led by Hegseth. He has been a vocal advocate for significantly reducing the U.S. military presence in Europe and withdrawing troops from Iraq and Syria.

The Pentagon recently announced an effort to identify leakers from within the Defense Department regarding “recent unauthorized disclosures of national security information.” The announcement said that the DoD would use polygraph exams to identify who was allegedly leaking sensitive or secret data.

“The use of polygraphs in the execution of this investigation will be in accordance with applicable law and policy,” DOD Chief of Staff Joe Kasper wrote in a memo. “This investigation will commence immediately and culminate in a report to the Secretary of Defense.”