The National Security Agency acted on its own authority, without a formal directive from President Bush, to expand its domestic surveillance operations in the weeks after the Sept. 11 attacks, according to declassified documents released Tuesday. The N.S.A. operation prompted questions from a leading Democrat, Representative Nancy Pelosi of California, who said in an Oct. 11, 2001, letter to a top intelligence official that she was concerned about the agency’s legal authority to expand its domestic operations, the documents showed. Full Story