This was CNBC's live blog tracking Sunday's developments on the war in Ukraine. See here for the latest updates. 

Finland will apply to join the NATO military alliance, the country's president said Sunday. It will be a historic move for the Nordic country, which has had a decades-long policy of military neutrality until now.

Joining the military alliance will "maximize" Finland's security after Russia's unprecedented invasion of Ukraine in February, President Sauli Niinisto said.

Ukraine's President Volodymyr Zelenskyy says he will speak to participants of the World Economic Forum in Davos next Monday, to discuss post-war reconstruction as his country continues to seek global support.

Earlier in the day, NATO's deputy secretary general struck a confident tone on Finland and Sweden — which is also expected to apply for membership — if they apply to join.

It comes after Ukraine's Foreign Minister Dmytro Kuleba met with U.S. Secretary of State Antony Blinken in Berlin, and said that more weapons and aid are on the way to Ukraine.

Zelenskyy to address World Economic Forum next week

Ukraine's president says he will be addressing participants of the World Economic Forum in Davos next Monday on May 23.

"This year the conference will be especially important for our country," Volodymyr Zelenskyy said in his nightly address on Saturday. "Post-war reconstruction will be discussed. We are doing our best to fully gather the support of the world, and participation in the Davos Forum is one of the best opportunities for that."

He acknowledged that as the war drags on, it has become even more important to "maintain the world's maximum attention to us, to Ukraine."

In a bid to garner more information and political support of Ukraine, Zelenskyy will be speaking to students from leading American universities on Monday, which include 63 from the U.S. and two from Canada.

"Their voice will definitely strengthen our capabilities," he said.

— Joanna Tan

Flood saves Ukrainian village from Russian occupation

The intentional flooding of a small village north of Kyiv that created a quagmire and submerged cellars and fields, but prevented a Russian attack on the capital, was worth all the sacrifice, residents said.

Ukrainian forces opened a dam early in the war in Demydiv, causing the Irpin River to flood the village and thousands of acres around. The move has since been credited with stopping Russian soldiers and tanks from breaking through Ukraine's lines.

"Of course, it was good," said a man who lives in the village, but would not reveal his name.

"What would have happened if they (Russian forces) .... were able to cross the little river and then went onto Kyiv?"

More than a third of some fields have been flooded, said another man, who also did not reveal his name.

Some two months later, people in the village were still dealing with the aftermath of the flooding, using inflatable boats to move around and planting whatever dry swaths of land were left with flowers and vegetables.

Children were left with wetlands to use as playgrounds.

— Reuters

British intelligence suggests Russia has lost a third of its ground forces in Ukraine

Russia has likely lost a third of its combat forces shipped into Ukraine as its campaign in the Donbas region continues to "lose momentum," British military intelligence said Sunday.

"Despite small-scale initial advances, Russia has failed to achieve substantial territorial gains over the past month whilst sustaining consistently high levels of attrition," the Ministry of Defence wrote on Twitter.

Among the setbacks, Russia's military faces low morale, high attrition rates and dwindling supplies of key equipment, which have further diminished the military's capabilities.

"Under the current conditions, Russia is unlikely to dramatically accelerate its rate of advance over the next 30 days," the ministry wrote.

Meanwhile, as shelling picked up Sunday in the Lviv region, Ukraine's President Volodymyr Zelenskyy remained hopeful that a Russian retreat is on the horizon.

"...Russian soldiers who survive will take this evil back to Russia," he said in a video posted to Telegram and translated by NBC.

"They will take it away because they will retreat. This is how all the feverish activity of the Russian military, which we see now, will end. And I am grateful to all the Ukrainian men and women, who are bringing this moment closer."

— Samantha Subin

Zelenskyy to speak with U.S., Canadian students on Monday

Ukrainian President Volodymyr Zelenskyy on Monday will speak with students from 63 U.S. and two Canadian universities, according to an NBC News translation of a Telegram post.

"We are doing everything to maintain the world's maximum attention to Ukraine," Zelenskyy said, also highlighting plans to address participants at the World Economic Forum on May 23.

"I will definitely continue to address the parliaments of European partner countries of Ukraine," he continued. "We are also working to extend the geography of such special speeches in parliaments to Africa and Asia."

— Kate Dore

McConnell expects Wednesday Senate vote for $40 billion Ukraine aid

U.S. Senate Republican Leader Mitch McConnell said he expected the Senate to vote on $40 billion in proposed aid to Ukraine on Wednesday after holding a related procedural vote on Monday.

"We expect to invoke cloture - hopefully by a significant margin - on the motion to proceed on Monday, which would set us up to approve the supplemental on Wednesday," McConnell told reporters on a conference call from Stockholm after visiting the Ukrainian capital on Saturday. He was referring to a procedural "cloture" vote that caps further debate on a matter to 30 hours.

— Reuters

McConnell says bipartisan Ukraine aid from Congress is 'not a charity'

Senate Republican leader Mitch McConnell said that Finland and Sweden would be "important additions" to NATO as he led a delegation of GOP senators to the region in a show of support against Russia's aggression.

McConnell also called on President Joe Biden to designate Russia a state sponsor of terrorism over its invasion of Ukraine.

The Republican leader also addressed the latest aid package for Ukraine.

Congress is working to approve $40 billion in military aid to Ukraine, a substantial infusion of support for the region. The measure includes $6 billion for Ukraine for intelligence, equipment and training for its forces, plus $4 billion in financing to help Ukraine and NATO allies build up their militaries.

McConnell said it is in America's interest to support Ukraine as he brushed aside criticism from some fellow Republicans, including former President Donald Trump, about the level of spending. It's a reemergence of the isolationist "America First" approach to foreign policy by a faction of the Republican Party.

McConnell said he told Zelenskyy that there is vast bipartisan support in Congress for helping Ukraine. "This is not a charity we're involved in here," McConnell said. "This is to prevent this group of thugs from beginning a march through Europe."

— Associated Press

McConnell and GOP senators to visit Helsinki Monday as NATO talks continue

Senate Republican leader Mitch McConnell and a delegation of GOP senators are due to visit Helsinki on Monday for talks with Finland's president as the previously neutral Nordic nation bordering Russia seeks NATO membership.

McConnell is a staunch supporter of the Western military alliance, and the visit by the Republicans who made a surprise stopover the weekend to Ukraine's capital delivers a show of American support for the region as Ukraine battles the Russian invasion.

The office of Finland's president, Sauli Niinisto, said Sunday that McConnell and Sens. Susan Collins of Maine, John Barrasso of Wyoming and John Cornyn of Texas will meet to discuss Finland's NATO membership, the Ukraine war and other issues. McConnell's office confirmed the visit.

— Associated Press

Sweden's ruling party backs joining NATO

STOCKHOLM — Sweden's ruling Social Democrats said on Sunday they backed the country joining NATO, abandoning decades of opposition in the wake of Russia's invasion of Ukraine and creating a large parliament majority in favor of membership.

With neighboring Finland already set to hand in its application, Prime Minister Magdalena Andersson is now all but certain to launch a formal application within days.

— Reuters

Ukrainian official says NATO has learned from its 'mistakes' in denying Ukraine membership

NATO's willingness to embrace Finland and Sweden into the military alliance shows the entity has learned from its historic treatment of Ukraine, Olga Stefanishyna, Ukraine's deputy prime minster for European and Euro-Atlantic integration, said on ABC's "This Week."

"The response from the allies — that this application will be considered and fulfilled immediately — only serves one very obvious argument: NATO has learned on the mistakes and the political mistakes which had been done back in 2008 in making promises without delivering on decisions," Stefanishyna said, contending that Ukraine's absence from NATO made it more vulnerable to Russian aggression.

In 2008, NATO promised Ukraine and Georgia that the two nations would one day join the defense collective. That has not happened, and Ukrainian officials including President Volodymyr Zelenskyy have increased their demands for membership since Russia's invasion began in February.

Finland, which shares a more-than-800-mile border with Russia, said Sunday it plans to formally apply for NATO membership. Sweden also is expected to follow suit soon.

— Kevin Stankiewicz

Ukraine not 'overoptimistic' despite Russian troops pulling back near Kharkiv, official says

Ukraine's deputy prime minister for European and Euro-Atlantic integration, Olga Stefanishyna, said she sees a "cautious amount of great news" in the country's defense against Russia. In particular, she pointed to Russian troops pulling back from around Kharkiv, Ukraine's second-largest city, in recent days.

"But we are not overoptimistic in that regard," she said in an interview on ABC's "This Week." "We see that Putin has readjusted his strategy, and the only possible winning scenario for him is a long-lasting war, which is not the case for us and the democratic world. ... The unconditional victory still remains the way forward."

Russia's navy remains in "full preparedness to continue shelling," Stefanishyna said, adding that "the bombarding of the eastern part of Ukraine, which are the major supply chains for the humanitarian and defense assistance, have been attacked over these nights."

— Kevin Stankiewicz

Putin appeared 'calm and cool' in phone call discussing Finland's NATO bid, Finnish president says

Russian President Vladimir Putin appeared "calm and cool" during a phone call discussing Finland's bid to join NATO, Finnish President Sauli Niinisto told CNN's "State of the Union."

"In the same way he confirmed that he thinks it's a mistake, we are not threatening you, altogether, the discussion was very, would I say, calm and cool," Niinisto said. "He didn't repeat those threats he had earlier and his people had been telling, that is that if Finland joins, that means some kind of military contra steps, whatever that meant."

The comments from Niinisto come just days after Russia said it would take "retaliatory steps" as Finland looks to sidestep years of neutrality and join NATO.

While Putin and Russia's response may not match the sentiment, Niinisto said he currently sees "no immediate problems."

"But in security policy, especially talking with Russia, you have to keep in mind that what he said doesn't mean that you shouldn't be all the time quite well aware and follow up what really is happening," he said.

Finland's attempt to join NATO faces potential obstacles from Turkey as President Recep Tayyip Erdogan has said the country does not "hold positive views" on the addition of Finland and Sweden. Niinisto said he is not worried the country will block Finland's bid.

— Samantha Subin

Ukrainian military using mannequins to bolster troop numbers on the frontlines

The Ukrainian military is using mannequins to bolster troop numbers on the frontlines. Ukrainian and Western officials say Russia is withdrawing forces around Kharkiv, Ukraine's second-largest city, suggesting it may redirect troops to Ukraine's southeast.

-Getty Images

EU’s Vestager says Ukraine war has revived the transatlantic relationship

Speaking to CNBC's Silvia Amaro, the European Commission's Executive Vice President for Competition Margrethe Vestager discusses the role of the EU-U.S. Trade and Technology Council, particularly given the ongoing conflict in Ukraine.

India open to exporting wheat despite ban, as Russia's war on Ukraine severely limits output

India said it would keep a window open to export wheat to food-deficit countries at the government level despite restrictions announced two days earlier.

India's Commerce Secretary B.V.R. Subrahmanyam told reporters the government will also allow private companies to meet previous commitments to export nearly 4.3 million tons of wheat until July. India exported 1 million tons of wheat in April.

India mainly exports wheat to neighboring countries like Bangladesh, Nepal and Sri Lanka.

A key aim of restrictions on exports is to control rising domestic prices. Global wheat prices have risen by more than 40% since the beginning of the year.

Before the war, Ukraine and Russia accounted for a third of global wheat and barley exports. Since Russia's Feb. 24 invasion, Ukraine's ports have been blocked and civilian infrastructure and grain silos have been destroyed.

At the same time, India's own wheat harvest has suffered from a record-shattering heat wave that is stunting production.

— Associated Press

Finnish president says his country will apply for NATO membership

In a press conference alongside Finnish Prime Minister Sanna Marin, President Sauli Niinisto said the country will apply for membership of NATO.

Joining the military alliance will "maximize" Finland's security after Russia's unprecedented invasion of Ukraine in February, he added.

"We have reached today an important decision," Marin said. "We hope that the parliament will confirm the decision to apply for NATO membership during the coming days."

The formal application is expected to be submitted to NATO next week.

Read the full story here.

— Katrina Bishop

More U.S. aid is on its way to Ukraine, foreign minister says after Blinken meeting

Ukraine's Foreign Minister Dmytro Kuleba has said additional aid from the U.S. is on its way after meeting with U.S. Secretary of State Antony Blinken in Berlin.

"More weapons and other aid is on the way to Ukraine," Kuleba tweeted.

"We agreed to work closely together to ensure that Ukrainian food exports reach consumers in Africa and Asia. Grateful to Secretary Blinken and the U.S. for their leadership and unwavering support."

Blinken is in Germany for the meeting of NATO foreign ministers this weekend.

— Katrina Bishop

Missiles hit military infrastructure in west Ukraine: Lviv regional governor

The governor of the region of Lviv, home to the largest city in western Ukraine, said a military facility nearby has been destroyed by Russian missiles.

"Four enemy missiles hit a military infrastructure facility in the Yavoriv district, near the border with Poland. The object is completely destroyed," Maksym Kozytsky wrote on Telegram, according to a Google translation.

There are not believed to be any victims, he added. The facility was located in the Yavoriv district, near the Polish border.

CNBC could not independently verify the claims.

The city of Lviv has largely escaped from the worst of Russia's invasion though it has not been completely spared.

As a result, it has become a refuge for many Ukrainians fleeing the devastation in the east of the country, where Russian forces appear to be focusing the majority of their efforts.

— Katrina Bishop

NATO deputy secretary general 'confident' on consensus over Finland and Sweden

NATO's deputy secretary general said Sunday that if Finland and Sweden decide to apply to join the military alliance, "will be able to welcome them."

Speaking to reporters as he arrived at the informal meeting of foreign ministers in Berlin, Mircea Geoana said the two countries were already the closest partners of NATO.

"I am confident that if these two countries will decide, in the next few days I understand, to seek membership in NATO, that [we] will be able to welcome them and to find all conditions for consensus to be met," he said.

Geoana described Turkey — whose President Recep Tayyip Erdogan has cast doubt on Sweden and Finland's potential membership — as an important ally.

"They expressed concerns that are addressed and discussed in between friends and allies," Geoana said.

Turkey joined NATO in 1952, and has the second-largest military in the 30-member alliance after the United States. 

Meanwhile, Finland's leaders on Thursday called for NATO membership "without delay" and neighboring Sweden is expected to follow suit, leaving it all but certain that the Scandinavian countries would soon abandon their traditional positions of neutrality toward both NATO and Russia in favor of joining the mutual defense pact.

— Katrina Bishop and Natasha Turak

Russia has lost one third of its original invasion force, UK estimates

Russia has probably lost a third of the ground combat force it originally committed to its invasion of Ukraine, and Moscow has little prospect of accelerating its advance in eastern Ukraine, according to an intelligence estimate from the British government.

Russia's attempted offensive in Ukraine's eastern Donbas region has lost momentum and "failed to achieve substantial territorial gains over the past month whilst sustaining consistently high levels of attrition," the U.K. Ministry of Defence said Sunday.

The Russian Ministry of Defense did not immediately respond to a CNBC request for comment.

The British assessment singled out destroyed Russian drones and river-bridging equipment as worsening the situation for Russian troops. "Russian UAVs are vital for tactical awareness and directing artillery, but have been vulnerable to Ukrainian anti-air capabilities," the U.K. Ministry of Defence said.

A Russian attempt to cross the Seversky Donets River in Ukraine's east last week was repulsed by Ukrainian defenders with heavy losses of equipment. Ukrainian officials on Thursday released a video showing burnt out vehicles and a destroyed pontoon bridge.

Low Russian morale and reduced combat effectiveness are exacerbating delays in its planned offensive, the British ministry said.

"Under the current conditions," the British ministry said, "Russia is unlikely to dramatically accelerate its rate of advance over the next 30 days."

— Ted Kemp

Ukraine wins Eurovision Song Contest

Ukrainian music act Kalush Orchestra won the 2022 Eurovision Song Contest.

Kalush Orchestra, which fuses hip hop with Ukrainian folk music, made a plea during the contest on behalf of people trapped in a steel mill in Mariupol, Ukraine, by a Russian siege.

Ukraine President Volodymyr Zelenskyy released a video cheering on his countrymen, saying "for us today, any victory is important," according to an NBC News translation of his remarks.

Performers from around the continent compete in the contest, each from a different country, and the winner is determined by a complicated voting system. This year's finale was held in Turin, Italy.

More than 180 million people watched the finale last year, according to Sky News.

— Ted Kemp

Russian forces retreating from around Kharkiv

Russian troops are withdrawing from around Ukraine's second-largest city after bombarding it for weeks, the Ukrainian military said Saturday, as Kyiv and Moscow's forces engaged in a grinding battle for the country's eastern industrial heartland.

Ukraine's military said the Russian forces were pulling back from the northeastern city of Kharkiv and focusing on guarding supply routes, while launching mortar, artillery and airstrikes in the eastern province of Donetsk in order to "deplete Ukrainian forces and destroy fortifications."

Defense Minister Oleksii Reznikov said Ukraine was "entering a new — long-term — phase of the war."

— Associated Press

Former MI6 officer and Trump dossier author Christopher Steele reportedly says sources tell him Putin is 'quite seriously ill'

Christopher Steele, a former MI6 officer and author of the Russian dossier on former President Donald Trump, told Sky News that his sources have said Russian President Vladimir Putin is "quite seriously ill" though the nature of the illness remains unclear.

"Certainly, from what we're hearing from sources in Russia and elsewhere, is that Putin is, in fact, quite seriously ill," Steele, who ran the Russia desk at MI6 in London between 2006 and 2009, told Sky News. "It's not clear exactly what this illness is — whether it's incurable or terminal, or whatever."

His comments come after Ukrainian Major General Kyrylo Budanov, in a separate interview with Sky News, said Putin is seriously ill with cancer and that a coup to remove him is under way in Russia.

CNBC was not able to independently verify these remarks.

Read the full Sky News report here.

— Terri Cullen

Ukraine band makes plea for Mariupol at Eurovision

Ukrainian band, Kalush Orchestra, made an impassioned plea to free people still trapped in a besieged steel mill in a strategic Ukrainian port city on Saturday night after performing in the final of the Eurovision Song Contest, where bookmakers tip them to win.

"I ask all of you, please help Ukraine, Mariupol. Help Azovstal, right now,'' the band's front man, Oleh Psiuk, said, to the live crowd of some 7,500, many of whom gave a standing ovation, and global television audience of millions.

The plea to free the remaining Ukrainian fighters trapped beneath the sprawling Azovstal plant by Russians served as a somber reminder that the hugely popular and at times flamboyant Eurovision song contest was being played out against the backdrop of a war on Europe's eastern flank.

President Volodymyr Zelenskyy gave signs that he was watching from Kyiv, and rooting for Ukrainian band.

"Indeed, this is not a war, but nevertheless, for us today, any victory is very important,'' Zelenskyy said, according to a .presidential statement. "So, let's cheer for ours. Glory be to Ukraine!"

Kalush Orchestra was among 25 bands performing in the Eurovision Song Contest final front of a live audience in the industrial northern city of Turin, while millions more watched on television or via streaming around the world.

The Ukrainian band was heavily tipped to win by bookmakers, who are giving the group that mixes traditional Ukrainian rhythms, costumes and dance moves with contemporary hip hop a 60% chance of winning.

— Associated Press

Read CNBC’s previous live coverage here:

Russia pulls back from Ukraine's second-biggest city; McConnell meets with Zelenskyy in Kyiv

— Katrina Bishop