Kremlin says it used hypersonic missiles for second time

President Joe Biden's trip overseas this week will include a stop in Poland, which borders Ukraine, the White House said late Sunday.

It was previously announced that the president would travel to Brussels to meet with NATO allies, European Union officials and leaders of the Group of Seven industrial nations to discuss support for Ukraine's defense against Russia's invasion.

The newly announced leg of the trip will have Biden going to Warsaw on Friday for a meeting with President Andrzej Duda, White House press secretary Jen Psaki said in a statement. She tweeted earlier that his travels would not include a stop in Ukraine.

The focus of the trip will be "international efforts to support Ukraine and impose severe and unprecedented costs on Russia for its invasion," according to Psaki's statement.

LVIV, Ukraine  — Russia demanded that Ukrainians in the besieged city of Mariupol lay down their arms Monday in exchange for safe passage out of town, but Ukraine rejected the offer.

The Russian demand came hours after it bombed an art school that was sheltering about 400 people, according to Ukrainian authorities.

Russian Col. Gen. Mikhail Mizintsev said his forces would allow two corridors out of the coastal city, heading either east toward Russia or west to other parts of Ukraine. Mariupol residents were given until 5 a.m. Monday to respond to the offer, which would have required them to raise white flags.

Russia didn’t say what action it would take if the offer was rejected. But Ukrainian Deputy Prime Minister Irina Vereshchuk said no. “There can be no talk of any surrender, laying down of arms. We have already informed the Russian side about this,” she told the news outlet Ukrainian Pravda. “I wrote: `Instead of wasting time on eight pages of letters, just open the corridor.’”

Mariupol Mayor Piotr Andryushchenko also rejected the offer, saying in a Facebook post that he didn’t need to wait until morning to respond and cursing at the Russians, according to the news agency Interfax Ukraine.

The Russian Ministry of Defense also said authorities in Mariupol could face a military tribunal if they sided with what it described as “bandits,” the Russian state news agency RIA Novosti reported.

Previous bids to allow residents to evacuate Mariupol and other Ukrainian cities have failed or have been only partially successful, with bombardments continuing as civilians sought to flee.

Biden has "no plans" to stop in Ukraine during his trip to Europe, White House press secretary Jen Psaki said Sunday.

The president is preparing to travel to Brussels this week to meet with NATO and G7 leaders as well as members of the European Council.

"The trip will be focused on continuing to rally the world in support of the Ukrainian people and against President Putin’s invasion of Ukraine, but there are no plans to travel into Ukraine," Psaki wrote in a tweet.

LVIV, Ukraine — Management of the Chernobyl nuclear power plant, site of the world’s worst nuclear accident in 1986, said Sunday that 50 staff members who had been on the job since the plant was seized by Russian forces on Feb. 24 have been rotated out and replaced.

Officials had repeatedly expressed alarm that the staff was suffering exhaustion after weeks of forced, unrelieved work and that this endangered the decommissioned plant’s safety.

The authority that manages the plant did not give specifics on how agreement was reached to let the workers leave and others come in to replace them.

An estimated 10 million people have fled their homes in the three weeks since Russia's war on Ukraine began, said the U.N. high commissioner for refugees, Filippo Grandi.

"Among the responsibilities of those who wage war, everywhere in the world, is the suffering inflicted on civilians who are forced to flee their homes," Grandi tweeted.

The U.N. had previously said more than 3.1 million people, including 1.5 million children, fled the country altogether since the war began. Grandi's number includes those who have been displaced within Ukraine's borders as shelling continues to bombard residential areas. 

LONDON — The bells of St. Paul’s Cathedral rang out Sunday as a gesture of support for Ukraine.

The London landmark rang its 12 bells at 4 p.m. local time, the same time as church bells were due to sound in the Ukrainian city of Lviv. Durham Cathedral in northern England and other churches around Britain also joined in.

Dean of St. Paul’s David Ison said he hoped Ukrainians would “find comfort in this act of solidarity.” He said “we continue to pray for strength and safety for the many people affected by the conflict, and for peace in Ukraine and around the world.”

Ukrainian politicians have likened their fight against Russian invasion to Britain’s struggle against Nazi Germany in World War II. One of the most iconic images of British wartime resilience is a photo showing the dome of St. Paul’s surrounded by thick smoke during a night of heavy German bombing in 1940.

Oksana Markarova, Ukraine’s ambassador to the United States, said Sunday that if Russia agrees to end its invasion of Ukraine and withdraws from the country, the issue of reparations and safety guarantees would need to be addressed.

Asked on CBS' "Face the Nation" to describe Ukraine's vision for an end to the war, Markarova said: "We need this to stop. They need to stop and get out from Ukraine. But we also need to be talking about reparations, about the security guarantees and everything else."

Amid peace talks between Ukraine and Russia this week, Secretary of State Antony Blinken signaled on NPR that a standard for lifting U.S. sanctions against Russia could include security guarantees.

"I will let Secretary Blinken to say what he said. But for us, clearly, it's a brutal attack," Markarova said. "We've lost people, many of our cities are destroyed and still are being destroyed."

JERUSALEM — Ukraine’s president called on Israel to take a stronger stand against Russia as he compared the invasion of his country to atrocities committed by Nazi Germany during World War II.

In a speech delivered Sunday via Zoom to members of Israel’s Parliament, Volodymyr Zelenskyy accused Russian President Vladimir Putin of trying to carry out a “permanent solution” against Ukraine. That was the term used by Nazi Germany for its genocide of some 6 million Jews.

Zelenskyy also noted that a Russian missile attack recently struck Babi Yar in Ukraine, where more than 30,000 Jews were slaughtered by the Nazis over two days in 1941. The site is now Ukraine’s main Holocaust memorial.

“You know what this place means, where the victims of the Holocaust are buried,” he said.

Israeli Prime Minister Naftali Bennett has emerged as a key mediator between Russia and Ukraine, in part because Israel has good relations with both countries.

Zelenskyy, who is Jewish, urged Israel to follow moves by Western countries to impose sanctions on Russia and provide Ukraine with weapons.

BERLIN — More than 8,000 people are attending an open-air concert in the German capital to express their support for Ukraine.

The “Sound of Peace” concert at the city’s landmark Brandenburg Gate on Sunday features German music stars such as Marius Mueller-Westernhagen, who was to perform his iconic song "Freiheit" ("Freedom"); violinist David Garrett; singer Peter Maffay; and the bands Revolverheld and Silbermond.

Up to 20,000 people were expected at the concert, which started in the early afternoon and is expected to last into the night.

As the afternoon wore on, police said the main streets leading to the venue became so crowded that newcomers should look for other ways to get to the concert, German news agency Deutsche Presse-Agentur, or dpa, reported.

Qin Gang, China's ambassador to the U.S., described a recent two-hour phone call between Biden and his Beijing counterpart, Xi Jinping, as "candid, deep and constructive."

Biden warned Xi during the call on Friday that there would be consequences for China if it provided “material support” for Russia following its invasion of Ukraine, according to senior administration officials.

"President Xi Jinping gave China's position very clear, that is China stands for peace, opposes war," said Gang on CBS's "Face the Nation" on Sunday, adding that China calls for "immediate cease-fire, and we are promoting peace talks."

Asked by moderator Margaret Brennan if China would send "money and weapons" to Russia in its bloody war against Ukraine, Gang indicated that China could send "foods, medicine, sleeping bags and baby formula" but "not weapons and ammunition to any party."

Artem Datsyshyn, a Ukrainian ballet dancer, died due to injuries following Russia's invasion last month, his employer said Thursday. 

Chief stage director at the National Opera of Ukraine Anatoly Solovyanenko confirmed Datsyshyn's death on Facebook, calling him a "wonderful man" and artist, according to a translation of the post.

His friend Tatiana Borovik said that Datsyshyn died in the hospital following a serious injury sustained from Russian attacks on Feb. 26. NBC News has not independently verified the cause of Datsyshyn's death. 

"Farewell my dear man," Borovik wrote in a translated Facebook post. "I can't express my heartache that is overwhelming me!"

Alexei Ratmansky, a former principal dancer with the Ukrainian National Ballet and world renowned choreographer, also expressed his grief on social media. In one comment, Ratmansky said he had been considering inviting Datsyshyn to join his show when he was last in Moscow, saying he was "furious" at the dancer's death.

"He was a beautiful dancer loved by his colleagues," Ratmansky said. "Unbearable pain."

Epic Games, the developer of the popular video game "Fortnite," tweeted that it would donate all its "proceeds from March 20, 2022, through April 3, 2022, to humanitarian relief for people affected by the war in Ukraine."   

NATO Secretary General Jens Stoltenberg said Sunday that any use of chemical weapons by Russia against the Ukrainian people would be a "blatant and brutal violation of international law," amid Western fears that Moscow might seek to use such weapons in the war.

"We know that Russia has used chemical agents in Europe before against their own political opponents,"  Stoltenberg said on "Meet the Press," warning that the alliance would take the possible action "extremely" seriously.

His remarks came after the Biden administration warned this month that Russia might use chemical weapons after the Russian Defense Ministry accused Ukraine of possibly planning to use such weapons of mass destruction. The White House said Moscow's allegations could be part of an effort to lay the groundwork for its own use of chemical or biological weapons against Kyiv.

Rep. Liz Cheney, R-Wyo., on Sunday urged the Biden administration to keep all options open to deter Russia. "We need to be very clear that we are considering all options and the use of chemical weapons is certainly something that would alter our calculation," she said on "Meet the Press."

Biden has said that Russia would pay a "severe price" if chemical weapons were used in Ukraine.

Zelenskyy approved a continuance to extend Ukraine's martial law order as Russia continues its offensive on the smaller country. 

The order begins on March 26, roughly a month after Putin's invasion began, and continues for an additional 30 days. Zelenskyy first issued his martial law declaration within hours of Putin declaring his "military operation" in Ukraine. 

Russia has been accused by Ukrainian authorities of indiscriminate shelling on residential areas, targeting civilian centers such as schools. Thousands of Ukrainian nationals and residents have fled the country over the past three weeks, running to the borders for safety as cities such as Kyiv and Mariupol endure heavy attacks. 

The conflict in Ukraine is "so devastating" that 10 million people have fled their homes, the United Nations High Commissioner for Refugees said Sunday.   

"Among the responsibilities of those who wage war, everywhere in the world, is the suffering inflicted on civilians who are forced to flee their homes," Filippo Grandi wrote in a tweet.

He added that the 10 million who had fled were "either displaced inside the country, or as refugees abroad."

KYIV, Ukraine — Mykhailo Podolyak, an adviser to Ukraine’s President Volodymyr Zelenskyy, says that six Russian generals and dozens of other senior officers have been killed since the start of the Russian invasion.

Podolyak tweeted on Sunday that “the high mortality rate among Russia’s senior military officers” reflects a “total lack of readiness,” adding that the Russian military relies on big number of troops and cruise missiles.

The Russian military hasn’t confirmed the death of any of its generals. But an associate and an officers’ group in Russia confirmed the death of one, Maj. Gen. Andrei Sukhovetsky, the commanding general of the 7th Airborne Division.

U.S. Ambassador to the United Nations Linda Thomas-Greenfield says negotiations between Russia and Ukraine toward a peace deal have remained one-sided.

"We have supported the negotiations that President Zelenskyy has attempted to do with the Russians and I do use the word attempted because the negotiations seem to be one-sided and the Russians have not leaned into any possibility for negotiated and diplomatic solutions," said Thomas-Greenfield on CNN's "State of the Union" on Sunday.

She added that she's "hopeful" Ukrainian efforts will "end this brutal war." 

Amid ongoing talks between Kyiv and Moscow, with the possibility that Ukraine could emerge as a country with no particular allegiance to Russia or the U.S.-backed NATO military alliance, Zelenskyy expressed some optimism a few days ago during his address to the U.S. Congress.

"The meetings continue, and I am informed, the positions during the negotiations already sound more realistic. But time is still needed for decisions to be in the interest of Ukraine," he said on Wednesday.

Dozens of elderly Ukrainians were killed when a Russian tank "cynically and deliberately" targeted a nursing home in eastern Ukraine earlier this month, the head of the Luhansk regional military administration said Sunday.

"They just adjusted the tank, put it in front of the house and started firing," Serhii Haidai said in a statement posted to his Telegram channel. The incident took place on Mar. 11, he said. 

He added that "56 people died on the spot" and 15 survivors were "abducted by the occupiers" before being taken to a "regional geriatric home" in Svatove. 

Russia has denied it is targeting civilians and NBC News has not been able to independently verify Haidai's statement. 

Pope Francis, continuing his implicit criticism of Russia, on Sunday called the conflict in Ukraine an unjustified "senseless massacre" and urged leaders to stop "this repugnant war".

"The violent aggression against Ukraine is unfortunately not slowing down," he told about 30,0000 people in St. Peter's Square for his weekly Sunday address and blessing.

"It is a senseless massacre where every day slaughters and atrocities are being repeated," Francis said in his latest strong condemnation of the war, which has so far avoided mentioning Russia by name.

"There is no justification for this," he said. "I beg all the players in the international community to truly commit themselves to stopping this repugnant war," he added. 

Francis also spoke about his visit on Saturday to a Rome hospital that is treating children wounded in Ukraine.

"One was missing an arm and another had a head wound," he said.

Russia's military said Sunday it had launched more strikes using hypersonic missiles on Ukrainian facilities. 

Hypersonic aeroballistic missiles fired by Kinzhal aviation missile systems hit a Ukrainian fuel depot in Kostiantynivka near the Black Sea port of Mykolaiv, defense ministry spokesman Maj. Gen. Igor Konashenkov said in a statement posted to the Kremlin's Telegram channel.

He added that the cruise missiles launched by Russian warships from the Caspian Sea were also involved in the strike on the fuel depot. 

Konashenkov said that more than 100 special operation officers and "foreign mercenaries" had been killed in the strikes.  

NBC News has been unable to verify his claims. 

It was the second day in a row that Russia said it used the Kinzhal, a system capable of striking targets 1,250 miles away at a speed 10 times the speed of sound. 

On Saturday, Russia's military said the weapon was used for the first time in combat to destroy an ammunition depot in western Ukraine.

Almost 40,000 people or around 10 per cent of Mariupol population fled the besieged port-city in the past week, the city's council said Sunday. 

The evacuees left in over 8,000 vehicles, most of them privately owned and traveled through a humanitarian corridor via the cities of Berdyansk to Zaporizhzhia "under continuous fire," Mariupol City Council said in a post on its Telegram channel. 

The strategic port city has been encircled by the Russian troops and faced a relentless bombardment for three weeks, coming to symbolize the horror of the Russian invasion of Ukraine.

Local authorities have said the siege has cut off food, water and energy supplies, and killed at least 2,300 people, some of whom had to be buried in mass graves.

Ukrainian President Volodymyr Zelenskyy said Sunday that the siege of Mariupol would go down in history for what he said were war crimes committed by Russian troops.

A Ukrainian child looks out of a tent while waiting for relocation after crossing the border into Romania on Saturday.

An art school sheltering 400 residents was hit by Russian shelling on Saturday, according to the city council in Mariupol. 

"Women, children and the elderly," were in the building, the council said in a post on its Telegram channel Sunday that was translated by NBC News.

"It is known that the building was destroyed, and peaceful people are still under the rubble," the post added. 

Russia has denied it is targeting civilians.   

Russia has increased its "indiscriminate shelling" of urban areas in the past week "resulting in widespread destruction and large numbers of civilian casualties," Britain's defense ministry said in an intelligence briefing Sunday. 

"It is likely Russia will continue to use its heavy firepower to support assaults on urban areas as it looks to limit its own already considerable losses, at the cost of further civilian casualties," the briefing said. 

It added that Russian forces continued to encircle cities in eastern Ukraine but had made "limited progress." 

KYIV — In peacetime, Ukraine has a thriving surrogate industry, one of the few countries where foreigners can get Ukrainian women to carry their pregnancies. Now at least 20 of those babies are stuck in a makeshift bomb shelter in Ukraine’s capital, waiting for parents to travel into the war zone to pick them up.

They’re well cared for at the moment. Surrogacy center nurses are stranded with them, because constant shelling makes it too dangerous for them to go home. Russian troops are trying to encircle the city, with Ukrainian defenders holding them off for now, the threat comes from the air.

Nurse Lyudmilla Yashchenko says they’re staying in the bomb shelter to save their lives, and the lives of the babies, some of whom are just days old. They have enough food and baby supplies for now, and can only hope and wait for the newborns to be picked up, and the war to end.

The city council of Mariupol, which has been battered by heavy shelling and attacks, alleged that several thousand residents have been deported to Russia over the past week. 

The allegation, which NBC News has not independently verified, was made in a post on the city council's Telegram account Saturday.  

"The occupiers illegally removed people from the Left Bank district and shelters in the building of the sports club, where more than a thousand people (mostly women and children) were hiding from the constant bombing," the post said, according to an NBC News translation.  

The council claimed some residents were captured and taken to cities in Russia.

In a portion of his latest address early Sunday, Ukraine's president appealed to Russians' humanity and sense of justice.

Speaking in Russian, his first language, Zelenskyy claimed 14,000 Russian soldiers have been killed in the invasion, which began Feb. 24. 

"This is 14,000 mothers," Zelenskyy said, according to an NBC News translation of his remarks. "This is 14,000 fathers. These are wives, these are children, relatives and friends. And you don't notice it? But there will only be more victims. As long as this war continues. Your war is against us, Russia against Ukraine. On our land."

Estimates of the number of Russian soldiers killed in the conflict have varied, and NBC News has not independently verified the death toll. 

It's not clear if Zelenskyy's appeals — this wasn't the first — hit their mark, but there have been signs of unease and even dissent in Russia, where President Vladimir Putin has cracked down on news media and all but banned displays of disagreement with the Kremlin.

Nearly 15,000 protesters have been arrested in Russia since the war began, according to OVD-Info, a Moscow-based human rights group that tracks police detentions.

Zelenskyy said at the top of his address, in Ukrainian, that the nation doesn't want to kill. 

“Ukraine has always sought a peaceful solution," he said. "Even more we are interested in peace now. Because we count everyone who is killed. Because it means something to us, every ruined family, every ruined house. Because we are Ukrainians, and for us a person is priceless."