Senators, spies and a president spent years in a pitched battle over how the history is told of one of the most controversial chapters of America's campaign against terrorism, the detention and interrogation of prisoners in secret C.I.A. jails. Congressional officials said on Friday that the [Trump] administration had begun returning to Congress copies of a 6,700-page Senate report from 2014 about the C.I.A. program. The move raises the possibility that most of the copies could be locked in Senate vaults indefinitely or even destroyed. The classified report [tells] the story of how ... the C.I.A. began capturing terrorism suspects and interrogating them ... beyond the reach of the American judicial and military legal systems. The central conclusion of the report is that the spy agency's interrogation methods - including waterboarding, sleep deprivation and other kinds of torture - were far more brutal and less effective than the C.I.A. described to policy makers, Congress and the public. The Senate Intelligence Committee, which was run by Democrats when the executive summary was released, sent copies of the entire report to at least eight federal agencies, asking that they incorporate it into their records - a move that would have made the documents subject to requests under the Freedom of Information Act. The agencies all refused to add the report to their records, and instead kept their copies locked up, prompting the American Civil Liberties Union to sue the C.I.A. for access to the full report.