Senior US intelligence officials believe with "a high level of confidence" that Russian President Vladimir Putin was personally involved in Moscow's efforts to interfere in the US presidential election.
Two senior officials, who had direct access to the information, told NBC News that intelligence reveals Putin personally organised how material hacked from Democrats was used and leaked. The officials said the intel came from diplomatic sources and spies working for allies of the US.
The hacking reportedly began as a "vendetta" against Hillary Clinton, a high-level intelligence source told NBC News. The hacking then developed into an effort to show corruption within the US political system as well as an effort to "split off key American allies by creating the image that [other countries] couldn't depend on the US to be a credible global leader anymore," the official added.
All 17 US intelligence agencies signed a statement in October claiming that Russia was responsible for the Democratic National Committee hack.
Since then, the CIA has determined that Russia aimed to influence the presidential election in favour of Donald Trump. However, the FBI has not endorsed the CIA's conclusion, although few are disputing that Russia aimed to hurt Clinton's White House bid.
The October statement claimed "only Russia's senior-most officials could have authorised these activities". According to NBC News, the US intelligence community now has information that places Putin at the helm of the hacking operation.
"It is most certainly consistent with the Putin that I have watched and used to work with when I was an ambassador and in the government," said former US ambassador to Russia Michael McFaul.
The former diplomat said doubt cast on the integrity of Russia's election by Clinton in 2011 led Putin to launch his revenge hacking scheme.
"He has had a vendetta against Hillary Clinton, that has been known for a long time because of what she said about his elections back in the parliamentary elections of 2011," McFaul said. "He wants to discredit American democracy and make us weaker in terms of leading the liberal democratic order. And most certainly he likes President-elect Trump's views on Russia."
President Barack Obama ordered a "full review" of Russia's involvement in the hacking earlier this month, while a CIA report detailing its confidence that Russia worked to undermine Clinton's campaign and push Trump closer to the White House prompted members of Congress to call for an independent investigation.
Senate Majority Leader Mitch McConnell and House Speaker Paul Ryan, both Republicans, dashed the call for an independent probe, but said an investigation into Russia's involvement would take place. Meanwhile, Trump has dismissed the reports that Russia worked to hack the election in his favour.