WARSAW — Vice President Kamala Harris called Thursday for an investigation into whether Russia had committed war crimes in Ukraine during a visit to a key NATO ally that has taken in more than one million refugees from the invasion.
President Andrzej Duda of Poland, standing beside Ms. Harris at a joint news conference in the capital Warsaw, said his country needed more direct assistance from the United States to support Ukrainians fleeing the war.
They both spoke after a meeting in which Ms. Harris sought to fortify the strong U.S. partnership with Poland, her top aides said, even after American officials said they were blindsided by a Polish offer to provide jet fighters to Ukraine, which Washington rejected out of fear that such a move could escalate the conflict.
“When it comes to crimes and violations of international norms and rules, we are also very clear that any intentional attack on innocent civilians is a violation,” Ms. Harris said when asked if there should be an international investigation into Russian war crimes. “Absolutely there should be an investigation and we should all be watching.”
The statement, one of the more forceful from a top Biden administration official describing Russia’s aggression, was part of an effort to portray a unified front with Poland, a NATO ally.
As the highest-ranking U.S. official dispatched to Eastern Europe since Russia attacked Ukraine, Ms. Harris’ visit to a country on the front lines of the war’s fallout further solidified her rise from a relative novice on the global stage to a top diplomat dealing with an international crisis.
Ms. Harris arrived in Poland a day after Poland’s surprising offer on Wednesday to hand over Russian-made MIG fighters to the United States so they could ultimately be transferred to Ukraine. But the Biden administration turned it down, trying to avoid anything that could be viewed by Moscow as escalation of U.S. or NATO military involvement in the war.
Poland’s proposal added another wrinkle to an already high-stakes diplomatic trip meant to reassure NATO allies. Ms. Harris echoed the Pentagon’s position that the fighter jets offer was not tenable during her closed-door meeting with Polish leaders, according to a senior administration official, and later told reporters the United States was “prepared to defend every inch of NATO territory.
“The United States takes seriously that an attack against one is an attack against all,” she said. The Biden administration was already gathering information on Russia’s attacks against civilians in Ukraine, according to a senior administration official, and sharing that with its partners.
Ms. Harris was referring to the ongoing investigation by the United Nations Commission of Inquiry when she called for a probe into Russia’s attacks, one of her officials later told reporters.
Pressed at the news conference about why Poland moved forward with the jet fighter offer without consulting the United States, Mr. Duda said his government was responding to a request from Ukraine. The Ukrainians have also asked NATO to impose a no-fly zone over their country to counter the threat from Russian military aircraft, but the alliance has so far refused to do so.
“We have to be a responsible member of the North Atlantic alliance — that’s why there were requests addressed to us,” Mr. Duda said, referring to NATO. “Those requests were addressed to us by the Ukrainian side,” he added. “We behaved as a reliable member of NATO should behave.”
One senior U.S. official, however, said the fighter jets would not be as effective for Ukraine as antiaircraft systems like Stinger missiles. Those systems have hampered Russia’s freedom to move in the air, while Ukraine’s anti-armor weapons have impaired freedom of maneuver on the ground.
“They’re just too old and they’re not state-of-the-art against relatively well-functioning Russian air defenses,” Jeremy Shapiro, research director for the European Council on Foreign Relations, said of the Soviet-era MIG fighter jets. “They’re basically extra targets.”
Still, some members of Congress have called on the Biden administration to deploy more weapons to Ukraine. Senator Mitt Romney, Republican of Utah, said the transfer of the aircraft from Poland to Ukraine would prevent further bloodshed.
“People are dying,” Mr. Romney said. “We need to get this aircraft immediately to the people of Ukraine. That’s what they are asking for.”
While the United States is against facilitating the transfer of the fighter jets, Ms. Harris’s top aides pointed to the decision to deploy two Patriot missile systems and roughly 4,700 additional American troops to Poland as evidence of the administration’s support for the country.
Still, the Russian attack has led roughly 1.3 million people to flee Ukraine for Poland so far, prompting the Polish government to propose paying citizens and organizations that host them about 250 euros, about $275, per month. Mr. Duda seized the moment with Ms. Harris to call on the Biden administration to do more to help with refugees.
He said he asked the vice president in their closed-door meeting to speed the processing of Ukrainian refugees who have relatives in the United States. Without more help from Western allies and the United Nations, he added, “this will end up in a refugee disaster.”
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His plea echoed that of resettlement organizations in the United States, which have called on President Biden to more rapidly repair a refugee system that was dismantled by the previous administration.
Some U.S. officials have said the immigration system is already strained by the pandemic, which limited the ability of immigration officials to process potential refugees overseas. Adding to the strains, more than 70,000 Afghans were given temporary protection in the United States after the fall of Kabul, officials have said.
The United States welcomed more than 11,400 refugees in fiscal year 2021, which ended last September. That was the lowest number in the history of the modern refugee system. The administration has admitted nearly 6,500 refugees in the last five months, according to the State Department.
“If Europe experiences the largest refugee crisis since the second world war, the U.S. has an opportunity to resume not just its global leadership but global humanitarian leadership,” said Krish Vignarajah, the president of Lutheran Immigration and Refugee Service, a U.S. resettlement agency.
Ms. Vignarajah said the U.S. embrace of Ukrainian refugees was particularly crucial “when countries that have far fewer resources like Poland have stepped up and absorbed a million refugees.”
Ms. Harris said the United States would send an additional $53 million in new humanitarian assistance to assist refugees in the region through the United Nations. The U.S. has provided roughly $159 million in humanitarian funds to Ukraine since October of 2020, according to the White House. During the joint press briefing with Mr. Duda, Ms. Harris also pointed to the $13.6 billion in emergency aid for Ukraine and European allies that passed the House of Representatives on Wednesday.
The vice president did not directly answer a question on whether the United States would commit to admitting a specific number of Ukrainian refugees.
The high-profile trip could serve to brandish the foreign policy credentials of Ms. Harris, who entered the White House widely seen as a potential front-runner for the Democratic presidential nomination in 2024, if President Biden does not run again.
Ms. Harris’s supporters last year grew concerned over that she was being tasked with challenges — such as addressing the root causes of migration — that could not be solved within four years. Some of her early work on addressing the poverty and corruption in Central America prompted a backlash from conservatives and Democrats alike.
She was criticized by immigration advocates when she traveled to Guatemala last year and told migrants “do not come” to the United States. But in recent months, the vice president has asserted herself on the global stage, traveling to France, Honduras, Germany and Poland. On Friday, she will visit Romania.
“I think Harris had a tough first year but it seems to me she’s starting to come into her own,” Mr. Shapiro said. Her recent trips were “real opportunities to demonstrate statesmanship and to show that she can serve the traditional role of U.S. vice presidents as someone who can carry the president’s message in an authoritative way.”
Eric Schmitt contributed reporting from Washington.