Moscow said on Monday that a meeting between Joe Biden and Vladimir Putin over the crisis at the Ukrainian border would be "premature", hours after agreeing to such a summit "in principle", as Ukraine called for sanctions to be rolled out even if Russia doesn't invade.
Kremlin spokesman Dmitry Peskov told reporters that "there is an agreement on the fact that we must continue the dialogue at the level of (foreign) ministers. Talking about concrete plans to hold summits is premature."
French President Emmanuel Macron had announced shortly before midnight after a day manning the phone for talks with Biden, Putin and other European leaders that the US and Russian presidents had agreed “in principle” to a meeting.
The Elysée added that the summit was to be prepared by US Secretary of State Antony Blinken and Russian Foreign Minister Sergei Lavrov when they meet on 24 February.
"It will only be held if Russia does not invade Ukraine," the Elysee Palace stressed.
White House press secretary Jen Psaki said afterwards the administration has been clear that “we are committed to pursuing diplomacy until the moment an invasion begins."
"And currently, Russia appears to be continuing preparations for a full-scale assault on Ukraine very soon," she added.
Meanwhile, the French and Russian presidents agreed in their call to "intensify" diplomatic efforts to resolve the crisis over Ukraine.
Putin blamed what he called Ukrainian "provocations" over heightened tensions in eastern Ukraine, the Kremlin said, and also demanded that the West take "seriously" Moscow's security demands.
The Elysée — which had previously described the conversation with Putin as a last-minute diplomatic effort to try to avoid a Russian invasion of Ukraine — said afterwards that both leaders had agreed on the need for a ceasefire, adding that "every day without war is a day won".
Macron also spoke to Ukraine's President Volodymyr Zelenskyy, who said on Twitter he was calling for an "immediate" ceasefire in the east and a resumption of OSCE-sponsored talks with Russia.
Ukraine urges EU to impose sanctions
Ukrainian foreign minister, Dmytro Kuleba urged the European Union on Monday morning "to impose some of the sanctions now.
“There are plenty of decisions that the European Union can make now to send clear messages to Russia that this escalation will not be tolerated and Ukraine will not be left on its own," Kuleba added from Brussels where the bloc's foreign ministers are gathering on Monday to discuss the crisis.
It comes as tensions have reached their highest point in some years in eastern Ukraine, amid a spike of violence over the weekend that has reinforced fears in the West that Russia may seek a pretext to invade its neighbour.
Russia extended military drills near Ukraine's northern borders, on the day Russian and Belarusian armies were due to end joint exercises in Belarus. However, Minsk said the drills would now continue because of the aggravated tensions in neighbouring Ukraine.
They began on February 10, adding to Western fears over Moscow's intentions, despite Putin's assurances that the exercises were "purely defensive". Russia has massed an estimated 150,000 troops along the Ukrainian border but denies planning to invade.
In other developments:
Ukraine formally denied on Monday that it had sent "saboteurs" to Russia after Moscow said it had killed five of them on its soil, a claim that risks further increasing the tensions between the two countries. "Not a single one of our servicemen has crossed the border into the Russian Federation, and not a single one of them has been killed today [in Russian territory]," Ukrainian Deputy Minister of Interior Anton Gerashchenko told reporters. Both Moscow and the separatist authorities in Donbas have accused Kyiv of several acts of sabotage and aggression since Saturday.
"The big question remains: does the Kremlin want dialogue?" asked European Council President Charles Michel on Sunday. He told the Munich Security Conference the West could no longer continue to offer an "olive branch" indefinitely when Russia was stoking tensions along the Ukrainian border. "One thing is certain: if there is further military aggression, we will react with massive sanctions,” he added.
US Secretary of State Antony Blinken, due to meet his Russian counterpart Sergei Lavrov later this week, told CNN that all evidence suggested "we are on the brink of an invasion", reiterating that NATO would be reinforced should that happen. Blinken told CBS that President Biden was ready to meet Putin "at any time, in any format, if that can help prevent a war".
US Vice President Kamala Harris said there was a "real possibility of war in Europe", the day after telling the Munich conference that the "foundation of European security is under direct threat in Ukraine". She also insisted that diplomatic channels remained open.
Israel became the latest country to call on its citizens to leave Ukraine. Austria, France and Germany have also told their nationals to leave. German airline Lufthansa has cancelled flights to Kyiv and the Black Sea port of Odessa. NATO’s liaison office in Kyiv said it was relocating staff to Brussels and to Lviv in western Ukraine.
UK Prime Minister Boris Johnson said on Saturday that Russia's plan could lead to "the biggest war in Europe since 1945". The US and UK would act to cut off Russian companies' access to dollars and pounds, he added.
Putin blames Ukrainian 'provocations'
Macron's phone call with Putin — which followed their meeting in Moscow on February 7 — lasted for an hour and 45 minutes, according to the Elysée.
"The two heads of state — this is very important — agreed on the need to re-establish the ceasefire," a spokesperson said. "We do not think that diplomacy's resources have expired."
According to the Kremlin, Putin blamed what he called Ukrainian "provocations" over the escalation in fighting with pro-Russian separatists in eastern Ukraine. He also demanded that NATO and the United States "take seriously" Moscow's demands regarding security — the issue at the heart of the current crisis.
In a statement, the Kremlin said that "modern weapons and ammunition being sent to Ukraine by NATO member countries" were encouraging Kyiv to pursue a military solution in the Donbas region, which in turn was forcing civilians to leave.
Russia wants guarantees that NATO will halt what it calls the alliance's eastward expansion, rule out membership for Ukraine and other former Soviet countries, and roll back its military deployments in central and eastern Europe.
Violence flares in eastern Ukraine
The past few days have seen a spectacular rise in skirmishes along the eastern front in Ukraine.
Hundreds of artillery shells have exploded this weekend along the contact line between Ukrainian soldiers and Russia-backed separatists in the conflict-ridden east, further increasing fears on Sunday that the volatile region could spark a Russian invasion.
It comes after international observers from the OSCE flagged more than 1,500 ceasefire violations on Thursday and Friday alone.
Separatist leaders in eastern Ukraine ordered a full military mobilisation on Saturday amid intensified violence in the war-torn region, while the evacuation of thousands of civilians into Russia has continued.
The Ukrainian army said two soldiers were killed and four injured on Saturday, the first fatalities in weeks, while mortar shells reportedly exploded near Ukraine's interior minister as he visited the front line.
Ukraine's foreign minister strongly denied that Ukrainian shells had landed in Russian territory, in response to reports in Russian media.
Western warnings echo in Munich
Western leaders stepped up their warnings at the Munich Security Conference over the prospect of a Russian invasion of Ukraine, accusing Vladimir Putin of seeking to undermine European security and overhaul international order.
"Ukraine will continue to follow only the diplomatic path for the sake of a peaceful settlement," President Zelenskyy said in his speech. He told President Macron in a phone call on Saturday night that he would "not retaliate" to Russian "provocations" in the east of the country.
The Ukrainian leader, who has called for a meeting with Putin, used the conference to call for an end to all "politics of appeasement" towards Russia.
European Commission President Ursula von der Leyen said Russian access to financial markets and high-tech goods would be sharply limited under Western sanctions being prepared in case of a Russian attack.
“The Kremlin’s dangerous thinking, which comes straight out of a dark past, may cost Russia a prosperous future,” she said.
US Vice President Kamala Harris heard pleas to increase US troop levels from Baltic leaders who worry their countries could be next in Russia's sights.
Lithuania's President Gitanas Nauseda urged the US, which has bolstered its troops' presence in the Baltics in recent weeks, to do even more and create a “permanent presence” in Lithuania. Currently, the US deploys a small contingent of troops to the country on a rotational basis.
Estonia's Prime Minister Kaja Kallas echoed that call. “We have lost our independence to Russia once, and we don’t want it to happen again,” she said.
President Biden — due to meet with his national security team on Sunday in Washington — said on Friday he was now "convinced" that Putin had made the decision to invade, despite Moscow's denials.