US president Joe Biden and Russian president Vladimir Putin will speak on Saturday, a White House official said, after Washington said earlier on Friday that Russia has massed enough troops near Ukraine to launch a major invasion.
"They will be speaking Saturday morning. Russia proposed a call Monday. We counter-proposed Saturday, and they accepted," the official told Reuters.
Russia is massing more troops near Ukraine and an invasion could come at any time, including during this month's Winter Olympics, Washington said on Friday as Moscow further stiffened its response to Western diplomacy.
Commercial satellite images from a private US company showed new Russian military deployments at several sites near Ukraine and, in his starkest warning yet to US citizens, president Joe Biden said he would not send troops to rescue any who remained there in the event of a Russian assault.
"Things could go crazy quickly," Mr Biden told NBC News.
Mr Biden held a phone call on the crisis with the leaders of Britain, Canada, France, Germany, Poland and Romania, as well as the heads of Nato and the EU.
Following that meeting and with alarm spreading, British prime minister Boris Johnson joined a handful of other nations in urging its citizens to leave Ukraine.
