Top Hegseth advisor Dan Caldwell placed on administrative leave by Defense Department

Caldwell previously worked at restraint-minded think tank Defense Priorities and Concerned Veterans for America, a group formerly led by Hegseth. A foreign policy realist, he has argued that the U.S. should dramatically reduce its footprint in Europe and pull out forces in Iraq and Syria. 

He wrote that "information identifying a party responsible for an unauthorized disclosure" would be referred for criminal prosecution.

Caldwell did not immediately reply to a request for comment. 

Caldwell's closeness to the defense secretary was underscored in the unintentionally leaked Signal chat on Houthi strikes, where Hegseth named him as the Pentagon point of contact for the offensive campaign.