The conclusions were part of a declassified intelligence report, ordered by President Obama, that was released Friday afternoon. Its main conclusions were described to Donald J. Trump by intelligence officials earlier in the day, and he responded by acknowledging that Russia sought to hack into the Democratic National Committee, but said nothing about the conclusion that Mr. Putin had sought to aid his candidacy, other than that it had no effect on the outcome.
The report, a damning and surprisingly detailed account of Russia’s efforts to undermine the American electoral system and Mrs. Clinton in particular, went on to assess that Mr. Putin “aspired to help President-elect Trump’s election chances when possible by discrediting Secretary Clinton and publicly contrasting her unfavorably to him.”
The report described a broad campaign that included covert operations, including cyberactivities, with “trolling” and “fake news.”
In the unclassified version of the report, the intelligence agencies also concluded “with high confidence” that Russia’s main military intelligence unit, the G.R.U., created the “persona” called Guccifer 2.0 and a website, DCLeaks.com, to release the emails of the Democratic National Committee and the chairman of the Clinton campaign, John D. Podesta.
Participating in the briefing were James R. Clapper Jr., the director of national intelligence; John O. Brennan, the director of the C.I.A.; Adm. Michael S. Rogers, the director of the National Security Agency; and James B. Comey, the director of the F.B.I.