Biden’s Poland Visit Spotlights Weapons, Humanitarian Aid for Ukraine

Russia’s Defense Ministry, meanwhile, said it had almost completed the first phase of its military operation in Ukraine and would move its focus to the country’s east, a signal that Moscow’s strategy may be shifting amid heavy losses and a stalled battlefield campaign.

At a hangar at Poland’s Rzeszow-Jasionka Airport, where antiaircraft missiles were stationed near the tarmac, Messrs. Biden and Duda spoke with humanitarian workers about the growing refugee crisis from the war. More than 3.7 million people have fled Ukraine, the United Nations said, with over 2.2 million arriving in Poland.

“What you, the humanitarian community, are doing is of such enormous consequence,” Mr. Biden said. “You’re helping millions of people and we must continue to scale up.”

The president on Thursday said the U.S. would take in 100,000 refugees fleeing Ukraine. After a Thursday meeting in Brussels, also attended by Mr. Biden, leaders of the Group of Seven industrialized countries called for greater international assistance for those countries neighboring Ukraine and most affected by the inflow of refugees.

Mr. Biden is expected to meet with some refugees in Warsaw on Saturday and hold a bilateral meeting with Mr. Duda.

The U.S. president also visited American troops who are in Poland to help provide greater protection in the face of Russia’s military operations in neighboring Ukraine. The U.S. has dispatched soldiers and Patriot missile defense systems to Poland, among other items. NATO has launched a strategic review that could lead to leaders agreeing to more permanently base troops in the countries closest to Russia, Belarus and Ukraine.

Mr. Biden told the troops Friday that their presence near Ukraine was a result of a broader conflict between democracies and autocracies in the world. “What you’re engaged in is much more than just whether or not you can alleviate the pain and suffering of the people of Ukraine,” he said.

“Are democracies going to prevail and the values we share, or autocracies going to prevail? That’s really what’s at stake,” he said.

Mr. Biden thanked service members of the 82nd Airborne Division at the G2A Arena, a conference center that is functioning as the division’s headquarters near the airport.

Rzeszow has become a major resupply artery for Ukraine. Military transport planes and other cargo aircraft are landing at a rapid pace in an airlift operation to bring in humanitarian aid and to funnel antitank weapons, heat-seeking antiaircraft missiles, communications and other supplies across the border with Ukraine about 60 miles east. The U.S. was joined by countries such as the U.K. and Germany to pledge to keep arms to Ukraine flowing.

On the eve of Mr. Biden’s arrival in Poland, a hulking Antonov cargo plane landed at the Rzeszow airport. It had departed from an airfield in Turkey, near the factory where TB2 Bayraktar drones are made that Ukraine has used to pummel Russian ground forces.

Ukrainian President

Volodymyr Zelensky

urged NATO allies on Thursday to ship more and better equipment as he joined the summit virtually. He asked for antiship weapons, planes, tanks, air defenses and systems that can fire barrages of ground rockets like the ones that Russia has used to target Ukrainian troops and cities.

The fighting in Ukraine has lasted far longer and been much fiercer than U.S. and allied officials had expected. Ukraine’s military has surprised its partners with its ability to repel Russian attacks, down its planes and destroy its tanks, keeping the invading army from making significant advances.

“The main goals of the first phase of the operation are complete,”

Sergei Rudskoy,

head of the Russian general staff’s main operational department said Friday, in a statement suggesting that Russia may be reassessing its ambitions after failing to take Kyiv, the strategic port city of Odessa or other major cities.

A senior U.S. defense official said the U.S. was still seeing airstrikes on the Ukrainian capital, but, “It appears that the Russians are at least at the moment not pursuing a ground offensive on Kyiv.”

The official also said the U.S. couldn’t confirm who was in control of the southern city of Kherson, the only regional capital so far captured by Russian forces.

“It doesn’t appear to be as solidly in Russian control as it was before. The Ukrainians are trying to take Kherson back,” the official said.

To Kyiv’s northwest, Ukraine continued its attempted encirclement of Moscow’s forces, drawing closer to allow for ambushes.

The Ukrainian military, including special forces and some Western fighters, made territorial gains to the west of the city, including in the town of Irpin, a battleground for weeks now, where some civilians braved artillery strikes by walking the streets. The head of Ukraine’s national police said authorities were clearing Irpin.

Russia made gains to Kyiv’s north and east, retaking the town of Izyum and shelling Kharkiv and Chernihiv, where Ukraine’s general staff said its troops were hindering a Russian advance on the capital.

Russia, which committed some 190,000 troops to the invasion of Ukraine last month, has lost as many as 40,000 of these troops between those killed in action, injured, captured or deserted, according to NATO estimates, a level of casualties that would render a large part of the Russian force incapable of offensive operations.

The Russian military said Friday that 1,351 service members have been killed in Ukraine, with 3,825 wounded, its first update on combat casualties in more than three weeks. The tally was more than double Moscow’s previous update but far lower than Ukrainian and Western estimates.

The toll on Ukraine’s civilian population has been immense. More than 1,000 people have been confirmed to have died in the month of fighting, with another 1,600-plus injured, the U.N. said, adding the actual number was likely much higher. Ten million people have been uprooted, the U.N. has said.

Municipal authorities in the Ukrainian city of Mariupol on Friday said about 300 people died in a theater that was bombed by Russian forces last week. Hundreds of civilians were using the theater’s basement as a bomb shelter when the Russian airstrike hit on March 16, according to Ukrainian authorities.

Mr. Biden, before leaving Brussels, also ramped up efforts to further punish Moscow for its attack, with the U.S. on Friday pledging to provide more liquefied natural gas to Europe this year to help free the continent from reliance on Russian energy. European states are moving to become energy independent from Russia, the continent’s most important energy supplier, to stop money flowing to Moscow. The U.S. is the world’s largest natural-gas producer.

—Matthew Luxmoore, Brett Forrest, Nancy A. Youssef and Alan Cullison contributed to this article.

Write to Tarini Parti at Tarini.Parti@wsj.com