US president Joe Biden has said any movement by Russian forces across the border into Ukraine would be considered to be an invasion, and that he has made this position clear to Russian leader Vladimir Putin.
Mr Biden’s comments on Thursday were the second attempt by the White House to walk back remarks made by the president at a press conference on Wednesday in which he suggested western countries may have different views on how to respond to a “minor incursion” by Russia into Ukraine.
Speaking on Thursday, Mr Biden said: “I’ve been absolutely clear with President Putin. He has no misunderstanding. Any, any assembled Russian units move across the Ukrainian border, that is an invasion.”
Mr Biden said such an invasion would be met by a “severe and co-ordinated response, economic response as discussed in details with our allies as laid out very clearly with President Putin”.
He added: “But there is no doubt, let there be no doubt at all, that if Putin makes this choice, Russia will pay a heavy price.”
Mr Biden said Ukraine “has a right to be” confident of US support.
Russia has massed about 100,000 troops close to its border with Ukraine, which the United States and western countries fear could be a prelude to an invasion. Russia has denied that it plans to attack Ukraine.
Russia has presented the West with a list of security demands and guarantees that it is seeking. However, talks last week with the US produced no breakthrough.
Mr Biden also indicated that Washington was keeping a close eye on other potential actions by Russia that did not involve open deployment of its troops.
“Russia has a long history of using measures other than overt military action to carry out aggression. Paramilitary tactics, so-called grey zone attacks and action by Russian soldiers not wearing Russian uniforms,” he said.
He said other potential covert action by Moscow included cyberattacks as well as what he called the deployment of “little green men” – Russian forces operating without any official identifying insignia.
“We have to be ready to respond to these as well in a decisive and united way with the range of tools at our disposal,” Mr Biden said.
Nato secretary general Gen Jens Stoltenberg said on Thursday that Mr Biden’s comments regarding a “minor incursion” were not a green light to a potential Russian invasion of Ukraine.
Earlier Ukrainian president Volodymyr Zelenskiy made clear that Mr Biden’s comments on Wednesday had not been received well in Kyiv.
“We want to remind the great powers that there are no minor incursions and small nations. Just as there are no minor casualties and little grief from the loss of loved ones,” he said in a tweet.
At his press conference on Wednesday Mr Biden said he thought that Russia would “move in” on Ukraine.