The seven-member delegation led by Rep. Stephen Lynch, a Democrat from Massachusetts, has visited reception centers for refugees from Ukraine in eastern Poland. They noted Poland's openness in accepting refugees from Ukraine, including in private homes. More than 2 million people fleeing war have come to Poland since Feb. 24, when Russia's troops invaded Ukraine.

“We are here to reassure and support the people of Ukraine. We are here to thank the people of Poland for the unbelievable generosity they have shown to the refugees,” said Lynch, who is chairman of the subcommittee on National Security in the Committee on Oversight and Reform.

During an online meeting with the media Saturday, the American lawmakers stressed the need to urgently assist Ukraine's military in their fight against Russian forces. They said there is no room for peace talks as long as there is a “hot war.”

“The most urgent action that we can take is to make sure that the Ukrainian fighters — those valiant patriots who are fighting for their freedom — have every bit of equipment, every bit of supply, every bit of support that we can possibly deliver to them,” Lynch said.

Answering a question about a potential peace mission in Ukraine, he said “there will be time for discussion, hopefully there will be time for diplomacy, but right now I think that the Ukrainian military is stepping up in a very heroic fashion against a much larger enemy."

U.S. President Joe Biden will attend an extraordinary NATO summit in Brussels on Thursday that is focused on the war in Ukraine and European security.

As long as Russian President Vladimir Putin continues the aggression, "there is only one way to respond to that and that's military force,” Lynch said.

Rep. Mark Green, a Republican from Tennessee who is on the House Armed Services Committee, had a message for Putin.

“You've united NATO, you've united the EU and you've united the United States Congress. We stand against your tyranny, your are a war criminal," Green said. "Withdraw your troops from Ukraine!”

Other members of the delegation included Democratic Reps. Lori Trahan of Massachusetts and Chellie Pingree of Maine and Republican Reps. Jake LaTurner from Kansas, Pat Fallon from Texas and Nancy Mace from South Carolina.