The Pentagon has launched a new investigation into leaks of classified information, warning that employees could face polygraph tests and potential criminal charges if found responsible. The move comes after national security disclosures were made public, though officials have not shared exactly what was leaked.

A memo from Defense Secretary Pete Hegseth’s chief of staff, Joe Kasper, was circulated Friday directing the Department of Defense to conduct a full investigation. The memo cited “recent unauthorized disclosures” and called for help from the Director for Defense Intelligence to coordinate with other departments and federal agencies on the probe.

Pentagon announces investigation into leaks, which could include polygraph tests https://t.co/N6K1j8aTmX

— Fox News (@FoxNews) March 23, 2025

President Donald Trump dismissed claims that his adviser, Elon Musk, would receive a classified briefing about potential U.S. military actions in a future conflict with China. The story had been reported earlier that day by The New York Times. Musk responded with a warning that those spreading “maliciously false information” would be caught and prosecuted.

The memo emphasized that if anyone is identified as responsible for leaking classified information, their case will be handed over for possible prosecution. Officials also noted that polygraph exams may be used in accordance with current laws and regulations.

🚨NEW: Department of Defense to polygraph employees in new investigation into leaks to media at the Pentagon.

Find them, prosecute them.

Leaks should not be tolerated.

🇺🇸

— Walter Curt (@WCdispatch_) March 23, 2025

Polygraph use is already under discussion in other parts of the government. Homeland Security Secretary Kristi Noem has pledged to increase the use of lie detector tests within her department to catch employees leaking sensitive operational details to the media.

The Justice Department is also now investigating what it called the “selective leak” of classified information related to the Tren de Aragua, a Venezuelan gang whose members are currently facing removal from the U.S. under the Trump administration.

Leaks have long been part of how Washington operates, often used by officials themselves to test how policy ideas might play with the public. But this latest investigation signals a tougher approach by the administration toward insider disclosures.

Polygraph tests are commonly used for national security clearances and federal employment, but they are not allowed as evidence in court or in military justice proceedings. The Supreme Court ruled in 1998 that they were too unreliable to be used in trials.

George Maschke, a former Army interrogator who founded AntiPolygraph.org, said the exams are prone to false positives and have been used over the years more as a tool to intimidate than to investigate. He pointed to a 1999 Pentagon report that expanded polygraph testing among defense personnel when leaks occurred.