Washington ? President Barack Obama on Tuesday ordered the federal government to rethink how it protects the nation’s secrets, in a move that was expected to declassify more than 400 million pages of Cold War-era documents and curb the number of government records hidden from the public.

Among the changes is a requirement that every record be released eventually and that federal agencies review how and why they mark documents classified or deny the release of historical records. A National Declassification Center at the National Archives will be established to assist them and help clear a backlog of the Cold War records by Dec. 31, 2013.

Obama also reversed a decision by President George W. Bush that had allowed the intelligence community to block the release of a specific document, even if an interagency panel decided the information wouldn’t harm national security.