US defence department workers could face lie detector tests as the Pentagon investigates alleged leaks of national security information.
The department's intelligence and law enforcement arms are carrying out the inquiry, which is the latest by Donald Trump's administration.
In a memo sent late on Friday, defence secretary Pete Hegseth's chief of staff called for an investigation into "unauthorised disclosures of national security information" that could include polygraph tests.
Earlier in the day, Mr Trump was forced to reject reports that Elon Musk would be briefed on US military plans for fighting a hypothetical war with China.
Mr Musk, who is head of the Department of Government Efficiency (DOGE) advisory group, visited the Pentagon on Friday to talk about "efficiencies" and "innovations", Mr Hegseth said.
Ahead of the meeting, the New York Times reported the tech billionaire would be briefed on plans for how the US would plan for a potential war with China - but this was denied by both Mr Musk and the president.
Mr Musk called the report "pure propaganda" and urged legal action against anyone leaking information.
The memo calling for an investigation said if it revealed information "identifying a party responsible for an unauthorised disclosure", that information could be used to seek criminal prosecution.
