US President Barack Obama has vowed to take action against Russia for its alleged interference in the US presidential election campaign.
"We need to take action and we will," he told US radio station NPR.
Russia stands accused by the US of hacking the emails of the Democratic Party and a key Hillary Clinton aide, which the Kremlin strongly denies.
Republican president-elect Donald Trump has also dismissed the claim as "ridiculous" and politically motivated.
The intelligence agencies say they have overwhelming evidence that Russian hackers linked to the Kremlin were behind the hacks.
And on Thursday, a White House spokesman said President Vladimir Putin was involved in the cyber-attacks.
Hours later, Mr Obama said: "I think there's no doubt that when any foreign government tries to impact on the integrity of our elections, that we need to take action and we will, at a time and a place of our own choosing.
"Some of it may be explicit and publicised. Some of it may not be.
"Mr Putin is well aware of my feelings about this, because I spoke to him directly about it."