The Pentagon has told journalists they must agree not to disclose unauthorised information or 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 to maintain their Pentagon press credentials.
The department said it remains committed to transparency to promote accountability and public trust but added that DoW information must be approved for public release by an appropriate authorising official before it is released, even if it is unclassified.
The guidelines necessitate that credentialed media acknowledge that determinations on press credentials may be based on unauthorised access or disclosure of classified national security information.
Chief Pentagon Spokesman Sean Parnell stated these guidelines reaffirm standards consistent with other military bases, aimed to protect sensitive information and national security.
Hegseth has faced scrutiny for previously mishandling sensitive information and the administration showed anger over leaked intelligence contradicting public statements about US military actions.
