Russia-Ukraine updates: 2 US veterans who joined Ukrainian forces missing

President Joe Biden confirmed Thursday that the White House is planning to send a senior official to visit Ukraine.

Before boarding Air Force One to fly to North Carolina, Biden was pressed for details by reporters but declined to elaborate.

“Well, we’re making that decision now. Thank you,” Biden said.

When a reporter asked who the White House will send to Ukraine, Biden quipped, "Ready to go?"

"Are you?" the reporter asked.

Biden responded, "Yeah," before boarding Air Force One.

Several world leaders have visited Ukraine in recent days and met with Ukrainian President Volodymyr Zelenskyy, including British Prime Minister Boris Johnson, Lithuanian President Gitanas Nauseda, Polish President Andrzej Duda, Latvian President Egils Levits and Estonian President Alar Karis.

-ABC News' Armando Garcia

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

Russian President Vladimir Putin said Thursday that attempts by Western countries to exclude Russian energy suppliers will affect the global economy and that European Union countries have no alternative resources.

"Consequences of such a step can become quite painful, first of all, for initiators of such a policy," Putin said during a meeting with top officials on the situation in the Russian oil and gas sector.

Putin claimed that Russian natural gas can't be replaced by alternative resources.

"What is surprising here: so-called partners from unfriendly countries assume that they can avoid Russian energy resources, including natural gas. Its reasonable replacement for Europe doesn't exist. It is possible, but it doesn't exist so far," Putin said. "Everyone understands there is no free volume (of energy resources) on the world market."

Putin said Moscow will redirect its energy eastward, as European countries try to reduce reliance on Russian exports.

"EU countries talk of cutting off energy supplies from Russia, driving up prices and destabilizing the market," Putin said.

Putin said that Russia should embark on building infrastructure for eastward oil and gas exports as the country needs to diversify its energy supplies away from Europe.

Thirty prisoners of war will be returned to Ukraine on Thursday as part of the latest exchange of captives with Russia, according to Ukrainian Deputy Prime Minister Iryna Vereshchuk.

Vereshchuk said in a statement via social media Thursday that, following an order from Ukrainian President Volodymyr Zelenskyy, five officers and 17 servicemen were exchanged, along with the release of eight civilians, including one woman.

"In total, 30 of our citizens are going home today," Vereshchuk said.

Thursday's prisoner swap marked the fourth to take place between the two countries since Russia launched an invasion of Ukraine on Feb. 24.