In a seven-year-old secret program at the National Archives, intelligence agencies have been removing from public access thousands of historical documents that were available for years, including some already published by the State Department. The restoration of classified status to more than 55,000 previously declassified pages began in 1999, when the Central Intelligence Agency and five other agencies objected to what they saw as a hasty release of sensitive information after a 1995 declassification order signed by President Bill Clinton. It accelerated after the Bush administration took office and especially after the 2001 terrorist attacks. But because the reclassification program is itself shrouded in secrecy -- governed by a still-classified memorandum that prohibits the National Archives even from saying which agencies are involved -- it continued virtually without outside notice until December. Historians say the program is removing material that can do no conceivable harm to national security. They say it is part of a marked trend toward greater secrecy under the Bush administration, which has increased the pace of classifying documents, slowed declassification and discouraged the release of some material under the Freedom of Information Act. I think this is a travesty," said Dr. Nelson. "I think the public is being deprived of what history is really about: facts."