Efforts to defuse the crisis in Ukraine via a frenzy of telephone diplomacy failed to ease tensions on Saturday, with US President Joe Biden warning that Russia faces "swift and severe costs" if its troops carry out an invasion. Follow our live updates below.
7:45am Paris time
US OSCE staff start pullout from Donetsk
US staff at the Organisation for Security and Cooperation in Europe (OSCE) started to withdraw by car from the rebel-held city of Donetsk in eastern Ukraine on Sunday, a Reuters witness said.
7:30am Paris time
Russia says warship chases US sub, Washington denies it
A Russian anti-submarine destroyer chased off a US submarine near the Kuril Islands, forcing it to leave the country's territorial waters, Moscow said Saturday, amid rising tensions over Ukraine.The US military denied the account.
Russia's defence ministry said that during planned military drills the Marshal Shaposhnikov destroyer had detected a US Navy Virginia-class submarine in Russian territorial waters near the Kuril Islands in the northern Pacific.
When the submarine ignored demands to surface, the crew of the frigate "used appropriate means" and the US submarine left at full speed, the ministry said, without providing further details.
The ministry said it had summoned the US defence attache in Moscow over the incident.
"In connection with the violation by the US Navy submarine of the state border of the Russian Federation, the defence attache at the US embassy in Moscow was summoned to the Russian defence ministry", the defence ministry said.
The statement from the US military, however, said: "There is no truth to the Russian claims of our operations in their territorial waters."
7am Paris time
Biden warns Putin invading Ukraine would bring 'severe costs'
"If Russia undertakes a further invasion of Ukraine, the United States together with our allies and partners will respond decisively and impose swift and severe costs on Russia," Biden told Putin, according to the White House.
While the United States was prepared to engage in diplomacy, "we are equally prepared for other scenarios," Biden said, as the two nations stare down one of the gravest crises in East-West relations since the Cold War.
The Biden-Putin talks were "professional and substantive," lasting just over an hour, but they produced "no fundamental change" in dynamics, a senior US official told reporters.
7am Paris time
Blinken says Ukraine embassy drawdown prudent
US Secretary of State Antony Blinken said on Saturday the risk of Russian military action in Ukraine is high and imminent enough to justify the departure of much of the staff at US embassy in Kyiv, which the State Department announced earlier.
"We ordered the departure of most of the Americans still at the US embassy in Kyiv. The risk of Russian military action is high enough and the threat is imminent enough that this is the prudent thing to do," Blinken told a news conference in Honolulu.
Most embassy staff were ordered to leave Ukraine immediately due to the threat of an invasion by Russia, with the department saying it appeared increasingly likely that the situation headed towards "some kind of active conflict."
This added to the State Department's call earlier this week for US citizens to leave Ukraine immediately.
7am Paris time
Australia evacuates final Ukraine embassy staff
Australia has directed all remaining embassy staff in Kyiv to evacuate, Prime Minister Scott Morrison said Sunday, as Russia continued to build up troops on its border with Ukraine.
The evacuation follows similar announcements from the United States and Canada, and comes after a frenzy of telephone diplomacy failed to ease mounting regional tensions Saturday.
Morrison said Australia would shift its operations to Lviv, a city close to Ukraine's border with Poland that is about 540 kilometres (336 miles) east of Kyiv.
He said the three remaining staff in Kyiv had been supporting "the many Australians [in Ukraine], many of whom are dual citizens".
"The situation, as you are all hearing, is deteriorating, and is reaching a very dangerous stage," he said.
While decrying "the autocratic, unilateral actions of Russia", the prime minister also pivoted back to regional politics, criticising China for "remaining chillingly silent on Russian troops amassing on the Ukrainian border".