The report also blames Russian Federation for the hack of the Democratic National Committee and the subsequent release of emails through organizations like Wikileaks: "We assess that the GRU operations resulted in the compromise of the personal e-mail accounts of Democratic Party officials and political figures".
They will be armed with a newly completed classified report that Clapper said on Thursday would include details of Russia's motivations - including whether the operation was partly meant to help elect Trump, as USA officials have said privately.
WASHINGTON-President-elect Donald Trump on Friday acknowledged for the first time that Russian Federation is among actors that try to hack USA government and political institutions, but insisted cyberattacks didn't affect the outcome of last year's election.
President-elect Donald Trump said that Russian Federation will respect the United States "far more than they do now" once he takes office, in a series of morning tweets following the release of an intelligence report on Vladimir Putin's role in the hacking of U.S. systems. The report, on Russian hacking and cyber activity, has not been made public, but unnamed officials spoke about it to multiple news organizations.
After meeting with intelligence officials, including Director of National Intelligence James Clapper, CIA Director John Brennan and FBI Director James Comey, Mr. Trump said in a statement Friday that the hacks had "no effect" on the results of November 8.
Trump on Wednesday sided with Assange and again questioned the US intelligence community's conclusion that Russian Federation tried to help his candidacy and hurt Clinton's. It is unclear from the Reuters story whether the report names those officials.
However, Mr Trump has repeatedly dismissed the allegation, challenging the intelligence experts who will aid him once he becomes president on January 20th.
They are expected to present the report to Trump on Friday in NY.
Trump subsequently tweeted his displeasure that NBC received access to the information in the report.
He told the New York Times on Friday, just hours ahead of the briefing, that the findings were part of a political "witch hunt" orchestrated by those hoping to undermine his victory.
Former Indiana Sen. Dan Coats, seen in November in Washington, will be appointed as the U.S. Director of National Intelligence, an office created after the September 11 attacks.
The intelligence agencies said Mr Putin likely had Democratic party emails hacked and information released as revenge against Mrs Clinton because he blames her for inciting mass protests against his regime in 2011 and 2012.
A heavily redacted, unclassified version of the report could be released as soon as Friday evening.