President Joe Biden met with the leaders of Sweden and Finland at the White House Thursday after the two countries submitted applications to join NATO.

"Today I'm proud to welcome and offer the strong support of the United States for the applications of two great democracies, and two close, highly capable partners to join the strongest, most powerful defensive alliance in the history of the world," Biden said.

Biden reaffirmed the U.S.'s support for the Nordic countries' applications to join the alliance.

"Finland and Sweden make NATO stronger not just because of their capacity, but because of their strong democracies and a strong united NATO is the foundation of America's security," he said.

Biden also sent a message to Russian President Vladimir Putin and Russia.

"So let me be clear: New members joining NATO is not a threat to any nation. It never has been. NATO's purpose is to defend against aggression, that's its purpose, to defend," Biden said.

-ABC News' Karen Travers and Justin Gomez

Vadim Shishmarin, 21, is back in court, one day after he pleading guilty to killing a 62-year-old Ukrainian civilian just days into the conflict.

Shishmarin confessed to the killing Thursday morning.

The widow of the victim testified in court that her husband meant everything to her, and she thinks the Russian soldier deserves life in prison, but if he gets exchanged for any of the Azovstal defenders she wouldn’t object.

"I feel very sorry for him," she said. "But for a crime like that -- I can't forgive him."

Shishimarin could spend the rest of his life in prison.

-ABC News' Joe Simonetti

Mass shelling of the Sumy region continued from Russian territory Wednesday evening, said Dmytro Zhyvytskyy, the governor of Sumy, on Telegram.

The shelling was along the entire border between the Sumy region and Russia, according to Zhyvytskyy.

Zhyvytskyy said Ukraine responded to the shelling appropriately and no casualties were reported.

-ABC News' Joe Simonetti

Mykhaylo Podolyak, an adviser to Ukrainian President Volodymyr Zelenskyy, told Russia not to offer Ukraine a cease-fire, because it would be impossible without Russian troops' withdrawal.

"Ukraine is not interested in new 'Minsk' and the war renewal in a few years," Podolyak said in a tweet, referring to the capital of Belarus and that country's allegiance to Russia. "Until [Russia] is ready to fully liberate occupied territories, our negotiating team is weapons, sanctions and money."

-ABC News' Joe Simonetti

White House national security advisor Jake Sullivan hinted Thursday of more sanctions coming against Russia in the "next week or two" aimed at targeting ways Moscow is evading sanctions already imposed.

“Where our focus will be over the course of the coming days is on evasion,” Sullivan said Thursday at the Economic Club of Washington. “As Russia tries to adjust to the fact that it’s under this massive economic pressure, what steps do they take to try to evade our sanctions and how do we crack down on that? And I think we'll have some announcements in the next week or two that identify targets that are trying to facilitate that evasion both inside Russia and beyond."

When Sullivan was asked whether sanctions will automatically be lifted if a negotiated peace deal between Russia and Ukraine is worked out, he appeared cautious with his words, saying, “a lot of that depends on what the shape and scope” of the agreement is.

“A lot of it depends on what the Ukrainians, in consultation with us and the Europeans come to agree to," Sullivan said. "You know, we're not going to do a deal over the head of the Ukrainians where we give a bunch of sanctions relief to Russia. But if some measure of sanctions relief were built in to some credible diplomatic solution led by the Ukrainians, that's something that we would happily discuss."

But Sullivan said Russian oligarchs shouldn't expect to ever get back their yachts and other assets seized under sanctions that have been imposed, saying the ultimate goal is "not to give them back” once the war is over.

“The president is actively looking at how we can deal with the fact that as we seize these assets, our goal is not to give them back. Our goal is to put them to a better use than that," Sullivan said. "But I'll be careful in what I say today because there's an ongoing kind of policy process around how we end up dealing with that question. But, rest assured, that the goal is not just to sit on them for a while."

-ABC News' Justin Gomez