Ukraine Humanitarian Crisis Worsens, as Biden Heads to Europe

Mr. Biden is set to land in Brussels Wednesday for a North Atlantic Treaty Organization summit before joining a meeting of the Group of Seven and then European Union leaders to unveil new sanctions on Russia.

Mr. Zelensky is scheduled to address the NATO gathering as part of weeks of outreach with politicians abroad to rally support for Ukraine. He has previously thanked NATO members for their support, while urging them to do more.

Mr. Zelensky also aims to hold talks with Chinese leader

Xi Jinping,

Ukraine’s presidential spokesman

Andriy Yermak

said. “Kyiv is hopeful Beijing will play a more prominent role in bringing this war to an end,” he tweeted.

Chinese Foreign Ministry spokesman

Wang Wenbin

said that Beijing is maintaining communication with relevant parties on the Ukrainian situation. “China will continue to play a constructive role in promoting the easing of the situation in Ukraine,” Mr. Wang said Wednesday.

The Russian and Ukrainian sides have been holding regular virtual meetings, with little sign of progress. Mr. Zelensky said that talks are “very difficult. Sometimes scandalous. But step by step we are moving forward.”

Russia’s Foreign Minister Sergei Lavrov on Wednesday said that negotiations with Kyiv were difficult, accusing the Ukrainian side of changing its negotiating position. Moscow wasn’t opposed to Western mediation in the negotiations with Ukraine, but Russia has clear red lines, Mr. Lavrov said, according to state newswire TASS.

He accused the West of looking to keep Russia engaged in hostilities for as long as possible by continuing to pump weapons into Ukraine. The U.S. and others have shipped arms and humanitarian assistance to Ukraine to help Kyiv fight off the Russian attack, helping the defenders exact a heavy toll on the invading military.

U.N. Secretary-General

António Guterres

on Tuesday said there were signs of progress on the diplomatic front. “There is enough on the table to cease hostilities—now…and seriously negotiate—now.” He called the war unwinnable, adding: “Sooner or later, it will have to move from the battlefield to the peace table.”

Mr. Biden, after the Brussels stop, heads to Poland on Friday, in part to discuss the refugee situation there with more than two million people having crossed the border from Ukraine over the past month to escape the fighting. Poland has been by far the largest recipient of people fleeing Ukraine, mostly women and children, United Nations and local officials have said.

The president’s trip unfolds as the humanitarian situation in some of Ukraine’s beleaguered cities worsened. The southern port city of Mariupol has been particularly devastated with Russian and Ukrainian forces locked in street-by-street warfare through the city’s downtown, as Moscow’s airstrikes gutted entire neighborhoods in its bid to take its first major urban center since launching its assault on Feb. 24.

Hundreds of people from Mariupol now arrive daily in Zaporizhzhia. They are fleeting in cars that show the scars of the conflict, arriving with shattered windshields and shrapnel damage.

Areas no longer controlled by Ukraine as of Friday

Direction of invasion forces

Controlled by or allied to Russia

Primary refugee crossing locations

Chernobyl

Not in operation

Ukraine territory, recognized by Putin as independent

Controlled by

separatists

Areas no longer controlled by Ukraine as of Friday

Direction of invasion forces

Controlled by or allied to Russia

Ukraine territory, recognized by Putin as independent

Primary refugee crossing locations

Chernobyl

Not in operation

Controlled by

separatists

Areas no longer controlled by Ukraine as of Friday

Direction of invasion forces

Controlled by or allied to Russia

Primary refugee crossing locations

Ukraine territory, recognized by Putin as independent

Chernobyl

Not in operation

Controlled by

separatists

Areas no longer controlled by Ukraine as of Friday

Direction of invasion forces

Controlled by or allied to Russia

Primary refugee crossing locations

Ukraine territory, recognized by Putin as independent

Areas no longer controlled by Ukraine as of Friday

Direction of invasion forces

Controlled by or allied to Russia

Primary refugee crossing locations

Ukraine territory, recognized by Putin as independent

Those left behind, about 100,000 people, are under constant shelling, “in a complete blockade” without food, water or medicine, said Mr. Zelensky, adding that violence is disrupting humanitarian efforts. Just over 7,000 people were able to flee the city Tuesday, he said, part of the more than 10 million people the United Nations says have been uprooted by the fighting, with more than 3.5 million crossing the border into neighboring countries and the rest displaced internally.

The fighting around Mariupol has been under way since the opening days of Russia’s assault, but the city has seen stepped-up levels of attack for about the past two weeks as the battle moved closer to the city. Mariupol has been a focus of the Russian offensive because it is a strategically important city linking Russian-controlled parts of eastern Ukraine with a swath of territory Moscow has captured in the south, and creating an arc containing much of the country’s Russian-speaking population.

The U.N. chief, in unusually blunt language, lamented what is going on in the city. “For more than two weeks, Mariupol has been encircled by the Russian army and relentlessly bombed, shelled and attacked. For what? Even if Mariupol falls, Ukraine cannot be conquered city by city, street by street, house by house.”

Much of Mariupol’s population remains trapped in the city, subjected to intensifying shelling from sea and air and on land, Mariupol mayor

Vadym Boichenko

said. “If previously only two planes were flying, now it’s five,” he said. “If there was only one ship approaching before, now there are four ships approaching. Also, there’s street fighting, including tanks, like in a bad dream from World War II.”

Many residents are fleeing the city by foot, Mr. Boichenko said, only to be blocked in the town of Manhush and outlying villages on the road to Berdyansk by armed men from the so-called Donetsk People’s Republic, a part of Ukraine occupied by Russia since 2014.

Russia’s Defense Ministry said Wednesday that it destroyed a large Ukrainian weapons arsenal, including equipment received from Western countries, near Rivne in northwestern Ukraine. The Russian military struck the arsenal with sea-based precision weapons, the ministry said.

Ukraine’s military said it was fighting to hold back Russian attacks across a range of locations, including Mariupol. Kyiv took further shelling overnight, local officials there said.

For weeks, Moscow’s offensive against Ukraine’s capital has stalled at the edge of the city and Russian troops, who approached from the north, have hunkered down in outlying suburbs. Rather than attack the city, they have tried to inch their way around it and cut off its defenders, laying siege to the city.

That encirclement has been unsuccessful and Ukraine has been able to keep some southern roads into the city open, said Oleg Zhdanov, a military analyst and reserve colonel in the Ukrainian army.

In the past few days Ukraine has been mounting a counterattack, he added, with Ukrainian forces attacking Russian troops north of Kyiv from the rear, in a wide pincer movement that could cut them off from the Russian border.

“Ukraine is now encircling the enemy that tried to encircle Kyiv,” he said.

—Brett Forrest, Qianwei Zhang and Evan Gershkovich contributed to this article.

Write to Isabel Coles at isabel.coles@wsj.com, Alan Cullison at alan.cullison@wsj.com and Georgi Kantchev at georgi.kantchev@wsj.com