The decision, effective immediately, prohibits accredited journalists from entering most Department of Defense headquarters in Arlington, Virginia, unless they have official approval and an escort, according to a statement from the Pentagon.
"While the Department remains committed to transparency, it is equally committed to protecting classified intelligence and sensitive information, the unauthorized disclosure of which could put the lives of American service members at risk," US Defense Secretary Pete Hegseth said in a memo.
Hegseth emphasized that protecting classified national intelligence information and operational security is "indispensable to the department."
The Pentagon Press Association, an organization representing the interests of journalists covering the US military, said the new rules appear to be a "direct attack on press freedom."
The association added in a statement: "The decision is said to be based on concerns about operational security. However, the Pentagon press corps has had access to unsecured and unclassified facilities there for decades, under both Republican and Democratic administrations, and in the aftermath of the September 11, 2001, attacks, without any concerns about operational security from the Department of Defense leadership," it said.
Since taking office last January, Donald Trump has imposed several restrictions on journalists and various media organizations.
The White House warned that Trump would not tolerate leaks of information to the media, and that federal employees who do so should be held accountable.
Trump also asked media organizations, such as the New York Times, the Washington Post, CNN, and NBC News, to vacate their Pentagon offices in a new rotation system that brought in other organizations, including the New York Post, Breitbart, the Daily Caller, and One America News Network.
On Friday, Reuters reported that the Trump administration had deployed lie detectors to investigate the leaking of unclassified information, and that some Department of Homeland Security officials had been informed that they were at risk of termination for refusing to submit to lie detector tests.
