Obama vows retaliation

Barack Obama vowed the United States would retaliate against Russian hacking after the White House accused Vladimir Putin of direct involvement in cyberattacks designed to influence the US election.

The outgoing US president's remarks on Thursday dramatically upped the stakes in a dispute between the world's leading nuclear powers over interference that may have swayed last month's tight election in which Republican billionaire Donald Trump defeated Democrat Hillary Clinton.

"I think there is no doubt that when any foreign government tries to impact the integrity of our elections that we need to take action," Obama told NPR radio.

"And we will, at a time and place of our own choosing."

Pointing the finger at the Russian president over meddling in the election also puts the White House on a collision course with Trump, who has become increasingly isolated in questioning Russian involvement in hacks of Democratic Party emails that appeared to have slowed the momentum of Clinton's campaign.

Obama is expected to be peppered with questions about the dispute and any subsequent action when he holds a news conference at 1:15 am today before leaving for a vacation in Hawaii.

"I don't think things happen in the Russian government of this consequence without Vladimir Putin knowing about it," one of his top advisers, Ben Rhodes, said Thursday.

"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," he told MSNBC television.

"And ultimately, Vladimir Putin is the official responsible for the actions of the Russian government."

The Kremlin yesterday slammed Washington for pointing the finger at Putin.

"At this point they need to either stop talking about this or finally present some sort of proof. Otherwise this looks extremely scurrilous," Putin's spokesman Dmitry Peskov told journalists during a visit to Japan.

White House spokesman Josh Earnest echoed his comments, saying the decision by US intelligence agencies in October to blame "Russia's senior-most officials" was not meant to be "particularly subtle."

Trump caused outrage in July by suggesting that Russia find 30,000 missing emails related to Clinton's use of a private server when she was secretary of state. Surrogates dismissed it as a joke, but he repeated his call on Twitter.

"I don't think anybody at the White House thinks it's funny that an adversary of the United States engaged in malicious cyber activity to destabilize our democracy. That's not a joke," Earnest said on Thursday.