The US says it is preparing “strong economic and other measures” over fears of a Russian invasion of Ukraine after Joe Biden and Vladimir Putin spoke.
In a video call, President Biden voiced worries over Russian troop build-ups near the border with Ukraine and called for a de-escalation of tensions.
Russia says it will not attack.
President Putin accused Ukraine of provocation and sought guarantees against eastward Nato expansion and deployment of weapons close to Russia.
More than 90,000 Russian troops are believed to be massed near Ukraine’s borders. The movement has strained already tense relations between Russia and the US.