US President Joe Biden and Russian leader Vladimir Putin will hold a video meeting on Tuesday amid American fears that Russia is planning to invade Ukraine.
“A lamentable state,” was how the Kremlin described US relations prior to the call.
Washington has accused Russia of amassing troops near the border with Ukraine to intimidate an aspiring Nato member and promises tough sanctions if Russia invades.
In a runup to the leaders' call, a senior US administration official said on Monday that Washington would consider additional military deployments and capabilities to Nato's Eastern Flank countries in an event of an invasion.
“In the event of a [Russian] invasion [into Ukraine], the need to reinforce the confidence and reassurance of our Nato allies and our Eastern Flank allies would be real, and the United States would be prepared to provide that kind of reassurance,” the US official said on a call with reporters.
The action would be based on a US-EU initiative that came together together after the Russian invasion of Crimea in 2014. The European Reassurance Initiative is centred around increasing the deployment of US forces and capabilities on Nato territory according to allies' requests.
But the US official stressed that the Biden administration is not seeking military confrontation with Russia, and that it does not know if Mr Putin has made the decision to invade Ukraine.
“We do not know whether President Putin has made a decision about further military escalation in Ukraine. But we do know that he is putting in place the capacity to engage in such such escalation should he decide to do so,” the senior official said.
The official also threatened joint US-EU economic sanctions on Russia if it proceeds with a military incursion.
“We believe that we have a path forward that would involve substantial economic countermeasures by both the Europeans and the United States that would impose significant and severe economic harm on the Russian economy, should they choose to proceed."
He added that Mr Biden will communicate this message to Mr Putin in Tuesday's call.
“There is a way forward here that will allow us to send a clear message to Russia, that there will be genuine and meaningful and enduring costs to choosing to go forward should.”
The senior official said Mr Biden will be speaking with key Europeans later on Monday to co-ordinate his message to Mr Putin, and US Secretary of State Antony Blinken will call Ukrainian President Volodymyr Zelenskiy in advance of the call.
For Moscow, the growing Nato embrace of a neighbouring former Soviet republic, and what it sees as the possibility of alliance missiles being stationed in Ukraine, is a red line.
Mr Putin has consequently demanded legally binding security guarantees that Nato will not expand further east or place its weapons close to Russian territory.
Washington has repeatedly said no country can veto Ukraine’s Nato hopes.
“I don’t accept anybody’s red lines,” Mr Biden said on Friday.
Some Russian and US analysts have suggested the leaders could agree to set up de-escalation talks, and the Kremlin has made it clear that it wants a Putin-Biden summit next year.
US Secretary of State Antony Blinken last week said that Washington had seen evidence Russia could be planning an invasion of Ukraine.
“We’re deeply concerned by evidence that Russia has made plans for significant aggressive moves against Ukraine,” Mr Blinken said after a meeting of Nato foreign ministers in Latvia’s capital Riga.
“Plans include efforts to destabilise Ukraine from within, as well as large-scale military operations.”
Mr Blinken accused Moscow of massing “tens of thousands of additional combat forces” near the border.
A Biden administration official told Reuters the US believed one option Mr Putin is weighing was a military offensive as soon as early 2022 involving 175,000 troops, armoured units and artillery.
The US estimated that half of those Russian units were already near the Ukrainian border, the same official said.