KYIV, Ukraine • The presidents of four countries on Russia’s doorstep visited Ukraine on Wednesday and underscored their support for the embattled country, where they saw heavily damaged buildings and demanded accountability for what they called war crimes carried out by Russian forces.

The visit by the presidents of Poland, Lithuania, Latvia and Estonia was a strong show of solidarity by the leaders of the countries on NATO’s eastern flank, three of them like Ukraine once part of the Soviet Union. The three traveled by train to the Ukrainian capital, Kyiv, to meet with their Ukrainian counterpart, Volodymyr Zelensky, and visited Borodyanka, one of the towns near Kyiv where evidence of atrocities was found after Russian troops withdrew to focus on the country’s east.

“The fight for Europe’s future is happening here,” Lithuanian President Gitanas Nauseda said, calling for tougher sanctions, including against Russia’s oil and gas shipments .

Elsewhere, in one of the most crucial battles of the war, Russia said more than 1,000 Ukrainian troops had surrendered in the besieged southern port of Mariupol, where Ukrainian forces have been holding out in pockets of the city. A Ukrainian official denied the claim, which could not be verified. Russia invaded on Feb. 24 with the goal, according to Western officials, of taking Kyiv, toppling the government and installing a Moscow-friendly one. But the ground advance slowly stalled and Russia lost potentially thousands of fighters in seven weeks of war. The conflict has killed untold numbers of Ukrainian civilians and forced millions more to flee. The fighting has also rattled the world economy, threatened global food supplies and shattered Europe’s post-Cold War balance.

A day after he called Russia’s actions in Ukraine “a genocide,” Biden approved $800 million in new military assistance to Ukraine, saying weapons from the west have sustained Ukraine’s fight and “we cannot rest now.” The weapons include including artillery systems, armored personnel carriers and helicopters.

Appearing alongside Zelensky in an ornate room in Kyiv’s historical Mariinskyi Palace on Wednesday, the European leaders — Lithuanian President Gitanas Nauseda, Estonian President Alar Karis, Poland’s Andrzej Duda and Egils Levits of Latvia — reiterated their commitments to supporting Ukraine politically and with military aid.

“We know this history. We know what Russian occupation means. We know what Russian terrorism means,” Duda said. He said those who committed war crimes as well as those who gave the orders should be held accountable.

From left: Lithuania’s President Gitanas Nauseda, Polish President Andrzej Duda, Ukrainian President Volodymyr Zelenskyy, Latvian President Egils Levits and Estonia’s President Alar Karis pose for a picture Wednesday during their meeting in Kyiv, Ukraine.

the associated press