The White House has suggested Russian President Vladimir Putin was directly involved in a hacking operation aimed at interfering with the US election.
Ben Rhodes, adviser to President Barack Obama, said that Mr Putin maintains tight control on government operations, which suggests that he was aware.
White House Press Secretary Josh Earnest added that it was “pretty obvious” that Mr Putin was involved.
Officials in Russia have repeatedly denied hacking accusations.
“Everything we know about how Russia operates and how Putin controls that government would suggest that, again, when you’re talking about a significant cyber intrusion like this, we’re talking about the highest levels of government,” Mr Rhodes said.
“And ultimately, Vladimir Putin is the official responsible for the actions of the Russian government.”
The Kremlin on Thursday bristled at claims that Mr Putin orchestrated the data breach with the hopes of influencing the US election outcome.
Analysis – Anthony Zurcher, BBC News, Washington
Democrats have struggled to grasp why Hillary Clinton lost. Could it be the spread of “fake news”? A poor Democratic ground game in Midwestern states? FBI Director James Comey’s last-minute letter to Congress about new Clinton emails?
Anything but acknowledge that Donald Trump turned out to be the more effective candidate with a more appealing message (at least in the states that mattered).
Russian government hackers are the latest culprit – or scapegoat, depending on one’s perspective. They’re a tempting target, however, given the latest accounts of intrigue from intelligence community sources. A wily Vladimir Putin overseeing damaging leaks makes for a deliciously villainous plot.
Of course those campaign emails, while certainly an annoyance to Democrats, likely weren’t enough to tilt the election. But that doesn’t mean these revelations won’t be a headache for a president-elect who bristles when challenged.
Now he’s feuding with his own intelligence services and lashing out on Twitter, virtually guaranteeing more leaks. A congressional investigation seems likely. There’s even talk of a Russian sanctions bill ending up on President Trump’s desk.
Mrs Clinton’s loss still stings, but for forlorn Democrats seeing Mr Trump squirm would be a salve for open wounds.
NBC reported that the US had evidence that Mr Putin personally directed how information hacked by Russian intelligence was leaked.
Dmitry Peskov, Mr Putin’s spokesman, told the AP the NBC report was “laughable nonsense”.
President-elect Donald Trump also continued to reject claims that Russian intelligence hacked into emails of the Democratic Party and of John Podesta, a key aide to presidential nominee Hillary Clinton.
The president-elect has dismissed a CIA report concluding that Russian hackers were trying to help Mr Trump win the election.
He tweeted on Thursday: “If Russia, or some other entity, was hacking, why did the White House wait so long to act? Why did they only complain after Hillary lost?”
However, the Obama administration on 7 October directly accused Russia of hacking US political sites and email accounts with the aim of interfering with the upcoming election.
The Department of Homeland Security and the Office of the Director of National Intelligence also released a statement asserting Russia had orchestrated the hack, including breaches on the Democratic National Committee and Democratic Congressional Campaign Committee.
The contents of those hacks, passed to Wikileaks and posted online, were embarrassing to the Democrats and shook up the presidential campaign.
The NBC report, which cited two unnamed senior officials, said the hacking campaign began as a “vendetta” against Mrs Clinton before becoming “an effort to show corruption in American politics and split off key American allies”.
Mr Putin is said to have been furious when Mrs Clinton, as secretary of state, questioned the integrity of 2011 parliamentary elections in Russia. He publicly accused her of encouraging street protests.
The BBC has not been able to confirm the NBC report.
There has been no specific evidence shared publicly to confirm Mr Putin’s role or knowledge of the hackings.