This is CNBC's live blog tracking developments on the war in Ukraine. See below for the latest updates. 

Russia's invasion of Ukraine entered its third month on Sunday, a conflict that has killed thousands and led to the worst refugee crisis Europe has seen since World War II.

The war will end only if Russian troops fully withdraw from the country, Ukrainian Prime Minister Denys Shmyhal said.

Meanwhile, U.S. Secretary of State Antony Blinken and Defense Secretary Lloyd Austin arrived in Ukraine to discuss military aid with Ukraine's President Volodymyr Zelenskyy.

The meeting with the senior U.S. officials was confirmed by Oleksiy Arestovych, a presidential adviser, in an interview on Ukrainian TV.

Ukraine is pressing the West for more powerful weapons to combat Russia's campaign to seize large swaths of the country's southern and eastern regions.

UK says Russia is planning a staged poll in a Ukrainian city to legitimize its occupation

Russia is planning a staged referendum in Kherson, Ukraine, to justify its occupation, the British defense ministry said in an intelligence update.

The southern city is important to Moscow's objective of establishing a land bridge to Crimea and dominating southern Ukraine, the U.K. Defense Ministry said in a tweet.

The Crimea peninsula, which Russia illegally seized control of in 2014, lies to the south of Ukraine between the Black Sea and the Sea of Azov. It is separated from Russia to the east by the narrow Kerch Strait.

The ministry noted that Russia previously held a "illegitimate referendum" in Crimea in 2014 to retrospectively legitimize the accession of the peninsula into the country.

"Russia's own domestic elections have been beset by allegations of vote rigging and have seen high-profile opposition blocked from running," the ministry added.

— Chelsea Ong

Zelenskyy congratulates Macron on re-election, calls him 'a true friend'

Ukraine's President Volodymyr Zelenskyy congratulated Emmanuel Macron on his re-election, saying the French president was a "true friend."

"Congratulations to the President and a true friend @EmmanuelMacron on the election victory," Zelenskiy wrote on his Twitter account in the early hours on Monday.

"I wish Emmanuel Macron new successes for the benefit of the French people. I appreciate the support of France and I am convinced: we are stepping together to new common victories! To a strong and united Europe!"

—Reuters

Zelenskyy meets top-level U.S. delegation, Ukraine official says

The U.S. secretaries of state and defense met Sunday night with Ukrainian President Volodymyr Zelenskyy in the highest-level visit to the war-torn country's capital by an American delegation since the start of Russia's invasion.

The meeting with U.S. Secretary of State Antony Blinken and U.S. Defense Secretary Lloyd Austin was confirmed by presidential adviser Oleksiy Arestovych in an interview on Ukrainian TV.

It came as Ukraine pressed the West for more powerful weapons against Russia's campaign in the Donbas region of eastern Ukraine, where Moscow's forces sought to dislodge the last Ukrainian troops in the battered port of Mariupol.

"Yes, they're meeting with the president. Let's hope something will be decided on further help," Arestovych said in an interview on Ukrainian TV.

Before the session, Zelenskyy said he was looking for the Americans to produce results, both in arms and security guarantees.

"You can't come to us empty-handed today, and we are expecting not just presents or some kind of cakes, we are expecting specific things and specific weapons,'' he said.

—Associated Press

Moldova struggles to deal with the fallout of Russia's war on Ukraine next door

The ongoing war next door has put the landlocked country of Moldova, a former Soviet republic and one of Europe's poorest nations, in a precarious position.

Moldova is Eastern Europe's smallest nation, with a population of fewer than 3 million and a landmass slightly larger than the state of Maryland. In less than two months, the country has been overwhelmed by hundreds of thousands of civilians fleeing Russia's ongoing military campaign.

"We are the most fragile neighbor of Ukraine because we are the country that is most affected and we are the country that has the fewest resources to deal with the situation and the fallout from the war," Moldovan Minister of Foreign Affairs Nicu Popescu said last week following meetings with Secretary of State Antony Blinken.

What's more, Moldova is 100% reliant on Russia's gas supply and 80% of the country's electricity comes from the Transnistria region, a heavily armed breakaway region controlled by Russia with borders touching Ukraine and Moldova.

Read the full story here.

—Amanda Macias

Ukraine calls for 'special' talks in Mariupol for trapped civilians and troops

Ukraine proposed a "special" round of negotiations with Russia to discuss the fate of the civilians and Ukrainian troops still trapped in Mariupol, an advisor to Ukraine's president said.

Ukraine wants to establish an immediate ceasefire in Mariupol, "multi-day" humanitarian corridors, and the freeing or swapping of Ukrainian fighters trapped in the Azovstal steel plant, presidential advisor Oleksiy Arestovych said in a video address.

—Reuters

UN chief Guterres discusses Ukraine with Boris Johnson ahead of Moscow visit

British Prime Minister Boris Johnson spoke with Antonio Guterres about civilian efforts in embattled areas of Ukraine ahead of the U.N. secretary-general's trip to Moscow.

Johnson and Guterres spoke about attacks on besieged areas of Ukraine, where it's been difficult to secure a ceasefire and facilitate humanitarian corridors, according to a readout of the call.

Guterres is set to meet Russian President Vladimir Putin and Foreign Minister Sergey Lavrov on Tuesday. He'll then travel to Ukraine to meet with Ukrainian President Volodymyr Zelenskyy and Foreign Minister Dmytro Kuleba on Tuesday.

Igor Zhovkva, an advisor to Zelenskyy, expressed doubts about the success of Guterres's visit to Russia, saying the UN doesn't speak for Ukraine in peace talks.

—Jessica Bursztynsky

Ukraine blames Russia after Mariupol humanitarian corridor fails

No humanitarian routes were established out of the besieged southeastern Ukrainian port city of Mariupol, Ukraine's Deputy Prime Minister Iryna Vereshchuk said, blaming Russian forces for not holding their fire.

Vereshchuk said the Ukrainian side would try again on Monday to establish safe passage out of Mariupol. She called for U.N. Secretary General Antonio Guterres, who is scheduled to travel to Moscow before visiting Kyiv this week, to demand a ceasefire and open up humanitarian corridors from Mariupol.

"This is what Guterres should talk about in Moscow, if he is preparing to talk about peace," Vereshchuk said.

—Reuters

War will end when Russia fully withdraws, says Ukrainian Prime Minister

The war in Ukraine will end only if Russian troops fully withdraw from the country, Ukrainian Prime Minister Denys Shmyhal said.

"We may protect democracy in Europe, on our continent, in the world but I think that this war should be finished when we clean our territories from Russian occupants," he said on CBS' "Face the Nation."

Shmyhal said it's "impossible to win" against a nuclear state like Russia, adding that Ukraine needs "guarantees of safety" from partners and opportunities to rebuild using frozen Russian assets.

Some members of Congress have proposed the use of seized Russian assets to pay for damages in Ukraine. Shmyhal said Ukraine is currently discussing this with the U.S. and other partners.

All of the damages, which Ukraine counts as a loss of GDP, should be paid for by Russia, Shmyhal said, adding that a country should pay anytime it attacks another.

"It should pay for this, absolutely, for everything," he said.

—Samantha Subin

Russia more 'interested' in genocide than peace talks: Ukraine PM

Ukrainian Prime Minister Denys Shmyhal said Russia won't be "interested" to negotiate when U.N. Secretary-General Antonio Guterres visits Moscow this week.

"I think the Russian Federation and Putin are not interested in this negotiation, they are interested in other things," Shmyhal said on CBS' "Face the Nation." "They are interested in genocide of Ukrainians, they are interested in the creation of a migration crisis in Europe and the world, they are interested in the creation of a food crisis, energy crisis. I'm not sure they are capable to hold this negotiation in a proper way."

The U.N. announced last week that Guterres will meet with Russian President Vladimir Putin on Tuesday in Moscow and then head to Ukraine to meet with Ukrainian President Volodymyr Zelenskyy. While speaking with top Russian officials, Guterres is expected to bring up failed humanitarian missions to evacuate civilians and efforts to bring in necessary aid.

Still, Ukrainian officials have been skeptical about the visit. Earlier in the day, Zelenskyy advisor Igor Zhovkva told NBC's "Meet the Press" that the U.N. chief is "not really" authorized to speak on behalf of the Ukrainian government and doesn't expect the peace talks to end with any result.

—Jessica Bursztynsky

Red Cross calls for 'immediate and unimpeded humanitarian access' to Mariupol, says it's 'deeply alarmed' by situation

The International Committee of the Red Cross said it was "deeply alarmed" by the ongoing situation in Mariupol, calling for "immediate and unimpeded humanitarian access" to allow civilians to exit the city.

"Each day, each hour that passes has a terrible human cost," the committee said.

The Red Cross said individuals in the area are in "dire need of assistance" and called for the safe passage of civilians and those in the Azovstal plant area.

Russia, which has claimed control of the besieged city, has reportedly resumed strikes on the Azovstal steel plant, where Ukrainian forces have holed up. Ukraine has also accused Russia of thwarting attempts to evacuate civilians from Mariupol.

The humanitarian group said it's prepared to help both parties negotiate "practical and workable arrangements" to evacuate civilians.

—Samantha Subin

Russia will face the same problems in Donbas it did in the west

Russia will face the same set of issues during its offense on the Donbas region as it did at the start of the invasion, former U.S. Ambassador to NATO Douglas Lute said.

"The problems that the Russian army demonstrated in phase one of this fight, in and around Kyiv, where they failed, the Ukrainians outmatched them, those same shortfalls by the Russian military I think will be on display again in Donbas," Lute said on ABC's "This Week."

"You can't reform an army in the matter of a couple of weeks," the retired Lt. General added. "This is the same Russian army, so I expect many of the same failures."

Since its invasion began in late February, Russian troops had been met with a slew of logistical problems and failed to capture Ukraine in the short time frame it anticipated. That led the army to pull back in some areas, regroup and focus on the eastern region.

—Jessica Bursztynsky

Zelenskyy advisor says weapons delivery is 'main subject' of upcoming visit with U.S. officials

Ukraine will prioritize weapons discussions when U.S. Secretary of State Antony Blinken and Defense Secretary Lloyd Austin are expected to visit Ukraine, said Igor Zhovkva, an advisor to Ukraine's President Volodymyr Zelenskyy.

Zelenskyy told reporters in Kyiv that the visit is slated for Sunday, though the U.S. has not confirmed the trip.

"The main subject of the discussion with our distinguished guests will be delivery of weapons," Zhovkva told NBC's "Meet the Press."

Zhovkva said Ukraine needs more anti-missile, anti-aircraft systems, and items to defend the skies. He said the country requires more artillery and tanks to protect cities like Mariupol.

Meanwhile, Zhovkva commented on UN Secretary-General Antonio Guterres's upcoming discussion with Russian President Vladimir Putin. He said Guterres is "not really" authorized to speak on behalf of the Ukrainian government and doubts the peace talks will end with any result.

—Samantha Subin

Pope Francis renews call for a truce as Orthodox Christians celebrate Easter Sunday

Pope Francis has renewed his call for an Easter truce as Orthodox Christians celebrated Easter Sunday, when the faithful mark the resurrection of Jesus.

Without naming countries, Francis urged aggressors to "stop the attack to help the suffering of the exhausted people."

Francis told a crowd gathered in St. Peter's Square in Vatican City that two months had passed since Russia's invasion of Ukraine and said that "instead of stopping, the war got worse. It is sad that in these days that are the holiest and most solemn for all Christians, the deadly clamor of arms is louder than the sound of bells announcing the Resurrection."

—Associated Press

Swiss reject Germany's arms export request

Switzerland has rejected two requests by Germany to export Swiss ammunition to Ukraine, citing the Alpine nation's strict neutrality.

The decision was first reported by Swiss weekly Sonntagszeitung.

Switzerland's State Secretariat for Economic Affairs confirmed that "both requests from Germany, whether the ammunition received from Switzerland can be passed on to Ukraine, were answered negatively with a reference to Swiss neutrality."

Germany needs Switzerland's consent for the arms delivery as part of the original sale contract. The Swiss office declined to specify what type of ammunition Germany had sought to export to Ukraine.

—Associated Press

Erdogan tells Zelenskyy that Turkey is ready to assist in negotiations

Turkey is ready to give all possible assistance during the negotiation process between Ukraine and Russia, President Tayyip Erdogan told Ukrainian leader Volodymyr Zelenskyy during a telephone call, the Turkish presidency said.

Erdogan said the evacuation of the wounded and civilians in Ukraine's Mariupol must be ensured, adding that Turkey viewed the guarantor issue positively in principle. Ukraine has sought security guarantees from various countries during talks.

—Reuters

Moscow says it struck arms depots in Kharkiv region, report says

Russia's defense ministry said its missiles struck nine Ukrainian targets overnight, according to Reuters, which includes four arms depots in the Kharkiv region where weapons were being stored.

Moscow said it had destroyed a further four arms depots in the same region and hit a facility in the Dnipropetrovsk region, the news agency reported.

—Matt Clinch

Russia continuously shelling Mariupol, Ukraine presidential advisor says

Mykhailo Podolyak, a presidential advisor in Ukraine, says Russia continues to shell the besieged city of Mariupol and has called for a "real Easter truce."

"Russia is continuously attacking the Mariupol Azovstal. The place where our civilians and military are located, is shelled with heavy air bombs and artillery," Podolyak said on Twitter.

Russian President Vladimir Putin earlier this week ordered his military to ditch a plan to storm the Azovstal steel plant, where several thousand Ukrainian troops, as well as civilians, are encamped, opting instead to continue to seal off the facility via blockade.

—Matt Clinch

UK intelligence says Ukraine has repelled Russian attacks in the east

The U.K.'s Ministry of Defence has given a weekly update on how things stand in the war in Ukraine after Russia entered a new phase and concentrated its attacks largely on the Donbas region in the east of the country.

In a series of tweets Sunday, the ministry said that Ukraine had repelled numerous Russian assaults along the line of contact, and had inflicted "significant cost" on Russian forces.

It also noted that "poor Russian morale and limited time to reconstitute, re-equip and reorganise forces from prior offensives" are likely hindering Moscow's combat effectiveness.

—Matt Clinch

UN chief to head to Turkey before meeting Putin and Zelenskyy

UN Secretary-General Antonio Guterres will visit Turkey on Monday, before heading to Moscow and Kyiv, the United Nations said.

"We need urgent steps to save lives, end the human suffering and bring about peace in Ukraine," the UN chief said in a tweet on Saturday.

Turkey has been a key mediator between Russia and Ukraine.

On Tuesday, the UN chief will meet Russian President Vladimir Putin and Foreign Minister Sergei Lavrov in Moscow.

He will then visit the embattled Ukrainian capital of Kyiv, where President Volodymyr Zelenskyy and Foreign Minister Dmytro Kuleba will see him.

Guterres will also be visiting UN staff on the ground to talk about how to increase humanitarian aid to the people of Ukraine.

—Joanna Tan

Pictures of Ukrainians in Lviv celebrating Easter food basket blessing

Orthodox Christians celebrate Easter Sunday on April 24. A day before, internally displaced Ukrainians are seen gathering at the Greek-Catholic church in Nadyby, Lviv to celebrate the traditional Easter food basket blessing on Saturday.

Many have fled from their homes and are taking temporary shelter at the church.

The UN's migration agency says that one in six people in Ukraine have been internally displaced.

In its latest report, the International Organization for Migration said more than 7.7 million people in Ukraine have been internally displaced since the war started in late February — that's some 17% of the country's population.

"Women and children, the elderly, and people with disabilities have been disproportionately affected as they all represent a highly vulnerable group of people," said Antonio Vitorino, director general of the agency.

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

—Joanna Tan

Ukraine says Moscow plans to conscript civilians in Russian occupied territories: UK intelligence

Ukraine has accused Moscow of planning to conscript Ukrainian civilians from the Russian-occupied regions of Kherson and Zaporizhzhia, according to the latest U.K. intelligence.

Moscow previously did the same in the Russian-occupied Donbas and Crimea, according to the report by the U.K. Defense Ministry. If true, it will be a violation of the Fourth Geneva Convention.

"Any enlistment of Ukrainian civilians into the Russian armed forces, even if presented by Russia as being voluntary or military service in accordance with Russian law, would constitute a violation of Article 51 of the Fourth Geneva Convention," the U.K. said in a tweet.

The article states that "the Occupying Power may not compel protected persons to serve in its armed or auxiliary forces," and "no pressure or propaganda which aims at securing voluntary enlistment is permitted."

—Joanna Tan

Zelenskyy says Austin, Blinken will visit Ukraine on Sunday

Secretary of State Antony Blinken and Defense Secretary Lloyd Austin will visit Ukraine on April 24 to discuss military aid, President Volodymyr Zelenskyy told reporters in Kyiv. It would mark the first time high-ranking U.S. officials have visited the nation's capital since the war began.

The Pentagon will not speak to the claim from Zelenskyy, according to two defense officials. The White House and the State Department had no comment.

Zelenskyy also reiterated calls for President Joe Biden to visit Ukraine. "We will also wait for security to allow the U.S. president to come and support the Ukrainian people," Zelenskyy said, according to a rough transcript of the news conference.

Top officials from other nations, including the U.K.'s Boris Johnson, have traveled to Ukraine to show support for Zelenskyy. The U.S. had reportedly been considering sending a top U.S. official to Ukraine in recent days.

—Jessica Bursztynsky

Read CNBC's previous live coverage here:

Senior U.S. government officials to visit Kyiv, Zelenskyy says; Ukrainians in Lviv celebrate Easter