Pentagon officials are living “in fear” of being forced to take polygraph tests to prove they are not leaking sensitive information to the media.

An email warning of the potential use of lie-detector testing has created an atmosphere of intimidation, according to one US defence source.

The source said the Pentagon was a “Pandora’s box” of uncertainty after the sacking of three top officials and the departure of two more high-ranking civilians in the past week, leaving Pete Hegseth, the defence secretary, without key advisers.

“The extraordinary thing is that lie detector tests are being threatened not to uncover potential anti-President Trump civil servants but to catch political appointees suspected of leaking classified or sensitive information,” the source said.

There are also concerns that the