US vice-president Joe Biden has suggested the Obama administration may launch a retaliatory cyber strike against Russia in response to what Washington believes to be interference by Moscow in this year’s election.

In an interview with NBC’s Meet the Press on Sunday morning, Mr Biden said “we’re sending a message” to Russian President Vladimir Putin about the election-related hacking. “He’ll know it.”

“We have the capacity to do it. It will be at the time of our choosing, and under the circumstances that have the greatest impact,” he told NBC.

This week the White House said the US would respond in a “proportional” way to the attempt to interfere in the election and that sanctions and covert action were under consideration.

Mr Biden’s interview is the clearest hint that the administration will seek to use its own offensive cyber capabilities to retaliate. Asked if the public would ever find out about the nature of the US response, he said: “Hope not.”

“Their capacity to fundamentally alter the election is not what people think,” Mr Biden said. “And I tell you what, to the extent that they do we will be proportional in what we do.”

Edward Snowden, the former National Security Agency contractor now exiled in Moscow, poked fun at this contradiction, noting on Twitter: “I get the feeling nobody told Joe Biden what ‘covert operation’ means.”