Top Pentagon advisor placed on leave amid investigation into leaks: report

The official told the outlet that Caldwell had been placed on administrative leave for "an unauthorized disclosure." The official said that "the investigation remains ongoing," and did not provide details into the nature of the alleged disclosure.

Hegseth’s chief of staff, Joe Kasper, signed a memo on March 21 requesting an investigation into "recent unauthorized disclosures of national security information involving sensitive communications." The possibility of a polygraph test was left open in the memo.

The memo for the Under Secretary of Defense for Intelligence and Security stated, "Recent unauthorized disclosures of national security information involving sensitive communications with principals within the Office of the Secretary of Defense (OSD) demand immediate and thorough investigation. I request the prompt assistance of your Director for Defense Intelligence (Counterintelligence, Law Enforcement, and Security) to support OSD in leading an investigation into unauthorized disclosures in coordination with the appropriate Department of Defense (DoD) stakeholders, including those responsible for maintaining and overseeing information security systems and in coordination with federal partners as required.

"The use of polygraphs in the execution of this investigation will be in accordance with applicable law and policy. This investigation will commence immediately and culminate in a report to the Secretary of Defense. The report will include a complete record of unauthorized disclosures within the Department of Defense and recommendations to improve such efforts. I expect to be informed immediately if this effort results in information identifying a party responsible for an unauthorized disclosure, and that such information will be referred to the appropriate criminal law enforcement entity for criminal prosecution."