Ukraine-Russia crisis: What to know amid a push for a summit

World leaders are making another diplomatic push in hopes of preventing a Russian invasion of Ukraine, even as heavy shelling continues in Ukraine's east and the Kremlin considered recognizing the independence of the separatist regions in eastern Ukraine.

The White House said President Joe Biden had agreed in principle to meeting with Russian President Vladimir Putin if he refrains from launching an assault on his neighbor that U.S. officials say appears increasingly likely.

A Biden-Putin meeting would offer some new hope of averting a Russian invasion that U.S. officials said could begin any moment from the estimated 150,000 Russian troops that have amassed near Ukraine.

The U.S. and Russian presidents have tentatively agreed to meet in a last-ditch diplomatic effort to stave off Moscow's invasion of Ukraine.

Yet but both seem cautious about a possible meeting.

The White House says the meeting will only happen if Russia does not invade Ukraine, noting that heavy shelling is continuing in eastern Ukraine.

Kremlin spokesman Dmitry Peskov, for his part, said Monday that it's premature to talk about specific plans for a summit.

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French President Emmanuel Macron sought to broker the possible meeting between Biden and Putin in a series of phone calls that dragged deep into the night. Macron's office said both leaders had accepted the principle of such a summit, to be followed by a broader summit meeting involving other leaders too.

U.S. Secretary of State Antony Blinken and Russian Foreign Minister Sergey Lavrov are to lay the groundwork for the summit at a meeting Thursday, according to Macron's office.

Heavy shelling has increased in recent days along the tense line of contact between Ukrainian forces and Russian-backed separatist rebels in Ukraine's eastern industrial heartland of Donbas.

It's a war that began in 2014 after Russia annexed Crimea from Ukraine. The fighting has claimed at least 14,000 lives but had been largely quiet for a while.

Ukrainian military spokesman Pavlo Kovalchyuk said Ukrainian positions were shelled 80 times Sunday and eight times early Monday, noting that the separatists were cynically firing from residential areas using civilians as shields. He said Ukrainian forces weren't returning fire.

In the village of Novognativka on the government-controlled side, 60-year-old Ekaterina Evseeva, said the shelling was worse than at the height of fighting.

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It's worse than 2014, she said, her voice trembling. We are on the edge of nervous breakdowns. And there is nowhere to run.

Putin convened top officials Monday to consider recognising the independence of the Russia-backed separatist regions in eastern Ukraine.

The meeting of the presidential Security Council comes amid Western fears that Russia could use the skirmishes in eastern Ukraine as a pretext for an attack.

Putin's statement follows televised statements by separatist leaders, who pleaded with Putin to recognize them as independent states and sign friendship treaties envisaging military aid to protect them from what they described as the ongoing Ukrainian military offensive. Russia's lower house made the same plea last week.

Ukrainian authorities deny launching an offensive and accuse Russia of provocation amid intensifying shelling along the line of contact.

Russian troops who have been carrying out military exercises in Belarus, which is located on Ukraine's northern border, were supposed to go home when those war games ended Sunday. But now Moscow and Minsk say that the Russian troops are staying indefinitely.

The continued deployment of the Russian forces in Belarus raised concerns that Russia could send those troops to sweep down on the Ukrainian capital of Kyiv, a city of 3 million less than a three-hour drive away from the Belarus border.

Despite Biden's assertion that Putin has made the decision to roll Russian forces into Ukraine, Ukrainian officials sought to project calm, saying that they aren't seeing an invasion as imminent.

Defense Minister Oleksii Reznikov said Monday that Russia has amassed 147,000 troops around Ukraine, including 9,000 in Belarus, arguing that the number is insufficient for an offensive on the Ukrainian capital.

The talk about an attack on Kyiv from the Belarusian side sounds ridiculous, he said, charging that Russia is using the troops there to create fear.

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Over the weekend at the Polish border, many Ukrainians were also returning home from shopping or working in the neighboring EU country. Some said they were not afraid and vowed to take up arms against Russia in case of an assault.

Ukrainian Foreign Minister Dmytro Kuleba said Monday that the European Union has agreed to set up a military education advisory mission in his country.

Kuleba told reporters in Brussels after meeting with the bloc's foreign ministers that an agreement had been reached in principle to roll out the advisory training military mission.

This is not combat forces. This is a new element in the cooperation between Ukraine and the European Union, he said, adding that details about the mission are still being decided. It is critical that we open this new page in our relations.

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The move could involve sending European officers to Ukraine's military schools to help educate its armed forces. It's likely to take several months to set up.

U.K. Foreign Secretary Liz Truss is warning that an invasion of Ukraine appears likely and that her country is preparing.

Diplomacy must be pursued but a Russian invasion of Ukraine looks highly likely. The U.K. and allies are stepping up preparations for the worst-case scenario. We must make the cost for Russia intolerably high, she wrote on Twitter.

Italy has renewed calls to its citizens urging them to leave Ukraine.

Italian media have been carrying interviews with Italians in Ukraine who have indicated a reluctance to leave because they have businesses, including restaurants, or are married to Ukrainians.

Foreign Minister Luigi Di Maio said in Brussels that the the Italian embassy in Kyiv is also carrying out rehearsals for evacuating its personnel, in case the country needs to take that step.

For now the the embassy remains fully operative because we believe in diplomacy and we want to give a clear signal of closeness to the Ukrainian people,'' Di Maio said.