Dozens of journalists who cover the U.S. Defense Department vacated their offices in the Pentagon and returned their credentials on Wednesday as new restrictions on press access took effect, writes Reuters.

The Defense Department had set a Tuesday deadline for news outlets to either sign a new Pentagon access policy or lose access to press credentials and Pentagon workspaces. At least 30 news organizations, including Reuters, declined to sign the new policy, citing a threat to press freedoms and their ability to conduct independent newsgathering on the world`s most powerful military. The policy requires journalists to acknowledge new rules on press access, including that they could be branded security risks and have their Pentagon press badges revoked if they ask department employees to disclose classified and some types of unclassified information.

The Pentagon Press Association, which represents more than 100 news organizations, including Reuters, said in a statement that Wednesday was "a dark day for press freedom that raises concerns about a weakening U.S. commitment to transparency in governance, to public accountability at the Pentagon and to free speech for all".

Chief Pentagon spokesperson Sean Parnell said in a statement on Monday: "The policy does not ask for them to agree, just to acknowledge that they understand what our policy is. This has caused reporters to have a full blown meltdown, crying victim online. We stand by our policy because it`s what`s best for our troops and the national security of this country".

The Pentagon declined to make additional comment on Wednesday. Journalists described the press area at the Pentagon on Wednesday as unusually quiet, as they removed furniture, computer servers, TV studio soundproofing material and other contents".