Biden Says Russian President Vladimir Putin ‘Cannot Remain in Power’

A White House official later walked back Mr. Biden’s comment. “The president’s point was that Putin cannot be allowed to exercise power over his neighbors or the region,” the official said. “He was not discussing Putin’s power in Russia, or regime change.”

Reuters reported that when asked about Mr. Biden’s remark, Kremlin spokesman Dmitry Peskov said, “That’s not for Biden to decide. The president of Russia is elected by Russians.”

Mr. Biden has made rallying European partners and other democratic nations against what he views as a threatening rise in authoritarianism a central focus of his presidency. As he wrapped up his European tour designed to demonstrate the West’s united support for Ukraine, the president reiterated that message.

“In the perennial struggle for democracy and freedom, Ukraine and its people are on the front lines, fighting to save their nation and their brave resistance is part of a larger fight for essential democratic principles that unite all free people,” he said in his speech.

In meetings this week of the North Atlantic Treaty Organization, the Group of Seven major economies and the European Union, Mr. Biden and other leaders together backed more military, financial and humanitarian assistance for Ukraine after Mr. Putin launched a full-scale invasion on Feb. 24.

But the unity among the Western leaders also began to show its limits, with differences emerging over how far to press their campaign of economic sanctions, particularly on targeting Russian energy exports.

“We must remain unified today and tomorrow and the day after and for the years and decades to come,” Mr. Biden said. “It will not be easy. There will be cost, but it’s a price we have to pay.”

Earlier in the day, Mr. Biden visited a Warsaw stadium, where thousands of Ukrainian refugees who have fled the fighting in their homeland are being processed, and discussed with Mr. Duda and senior Ukrainian officials how Washington can bolster its military and humanitarian assistance to both countries.

“He’s a butcher,” Mr. Biden said of Mr. Putin. He was speaking with reporters after meeting with refugees, including some from the Ukrainian southern port city of Mariupol, which has seen weekslong Russian bombardment and attacks on civilians.

Mr. Peskov, the Kremlin spokesman, in remarks carried by Russia’s state-run TASS news agency, responded to Mr. Biden: “Such personal insults are narrowing down the window of opportunity for our bilateral relationship under the current [U.S.] administration.”

Mr. Biden has previously called Mr. Putin a “war criminal.” His comment was formalized days later, with the U.S. government accusing Russia of war crimes. Moscow summoned U.S. Ambassador

John Sullivan

on Monday to hand him a note of protest over Mr. Biden’s comment, and Russia’s Foreign Ministry warned that relations between Moscow and Washington were “on the verge of a rupture.”

Warsaw has become the epicenter of Europe’s largest refugee crisis since World War II. More than 300,000 people from Ukraine have arrived in the Polish capital since Russia’s invasion, a population that would amount to every sixth resident in the city if they stayed. Overall, more than 3.7 million people have fled Ukraine, the United Nations said, with over 2.2 million arriving in Poland.

The administration said Thursday the U.S. would take in 100,000 refugees fleeing Ukraine, but officials haven’t yet finalized the details of the plan and are looking at a range of legal pathways. Warsaw’s mayor met with the president and discussed the strains the influx of hundreds of thousands of people, half of them children, has placed on the city and its services.

At a meeting on Thursday in Brussels, G-7 leaders, including Mr. Biden, called for greater international assistance for those countries neighboring Ukraine and most affected by the inflow of refugees.

While in Warsaw, Mr. Biden stayed in a hotel across from the central train station that has become packed with refugees arriving from the war, with many sleeping on blankets on its floor.

Mr. Biden joined a meeting on Saturday that Secretary of State

Antony Blinken

and Defense Secretary

Lloyd Austin

held with Ukrainian Foreign Minister

Dmytro Kuleba

and Ukrainian Defense Minister

Oleksii Reznikov.

He also held a bilateral meeting with Mr. Duda.

As Mr. Biden was in Poland, Saturday, two Russian missiles struck the Ukrainian city of Lviv just 40 miles east of the Polish border. The casualties and damage from that attack weren’t immediately clear, but the assault brought the war precariously close to NATO and European Union territory.

The president updated Ukrainian officials on his meetings this week in Brussels with allies and discussed the new sanctions the U.S. imposed on Russia, along with “further efforts to help Ukraine defend its territory,” according to the White House.

“We have learned from sad experience in two world wars: When we’ve stayed out of and not been involved in stability in Europe, it always comes back to haunt us, the United States,” Mr. Biden said in his meeting with Mr. Duda.

Russia’s Defense Ministry said Friday 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 might be shifting amid heavy losses and a stalled battlefield campaign, as Mr. Biden also visited American troops who are in Poland.

The U.S. has dispatched soldiers and Patriot missile defense systems to Poland, among other items, to help provide greater protection in the face of Russia’s military operations in neighboring Ukraine.

Warsaw’s government and people are overwhelmingly supportive of Ukraine, with ads on public buses carrying a quote attributed to Ukraine’s President

Volodymyr Zelensky,

“I need ammunition, not a ride.”

Grocery stores have installed boxes where Poles can drop off food for refugees, and coffee shops bear posters asking customers to chip in to pay for night vision goggles and helmets for Ukraine’s Territorial Defense units. The words “We are with you,” in Polish and Ukrainian, are printed on billboards across the city.

Write to Tarini Parti at Tarini.Parti@wsj.com and Drew Hinshaw at drew.hinshaw@wsj.com