The Pentagon has told journalists they must agree not to disclose unauthorized information or else risk losing access to the building.
The change is among a number of new restrictions, which also seek to impose limits on the movement of journalists within the facility, which is home to the Department of War, formerly known as the Department of Defense.
It follows a series of leaks in recent months.
Pete Hegseth, who was recently given the new title of Secretary of War, said on social media: The 'press' does not run the Pentagon — the people do. The press is no longer allowed to roam the halls of a secure facility. Wear a badge and follow the rules — or go home.
The new restrictions were set out in a briefing note sent to members of the press, which they will be required to sign in order to maintain their Pentagon press credentials.
The department said it remains committed to transparency to promote accountability and public trust. However, it added: DoW information must be approved for public release by an appropriate authorising official before it is released, even if it is unclassified.
It asks signatories to acknowledge that determinations on press credentials for the building may be based on the unauthorised access, attempted unauthorised access, or unauthorised disclosure of classified national security information, or information designated as controlled unclassified information.
These guidelines are said to align with standards at other military bases across the country, with Chief Pentagon Spokesman Sean Parnell labeling them as basic and common-sense guidelines aimed at protecting sensitive information and ensuring national security.
Hegseth has previously faced scrutiny for his own handling of classified information, raising questions about the integrity of information shared within his circles.
The administration's frustration became evident in June when a leaked intelligence report seemingly contradicted its public statements regarding the implications of US strikes on Iran's nuclear programme.
