(VILNIUS, Lithuania) — President Joe Biden will make a major speech Wednesday following a two-day, high-stakes NATO summit in Vilnius, Lithuania.

Biden will speak on the strength of the alliance and the importance of continued support for Ukraine against Russian invaders, as well as other major global challenges, according to National Security Council Senior Director for Europe Amanda Sloat.

“He’ll talk about how NATO is more vital to our shared future and that didn’t happen by accident,” Sloat added, telling reporters it would be a “memorable speech.”

All eyes were on Biden earlier Wednesday as he met with Ukrainian President Volodymyr Zelenskyy. The Ukrainian leader said he had a “good, powerful” discussion with Biden that ran twice as long as scheduled.

Despite his earlier harsh tone over the lack of a clear timeline for Ukraine to join the alliance, Zelenskyy said he felt satisfied with the outcome of the summit as he sat alongside Biden.

“We have great unity from our leaders and security guarantees, that is a success for this summit, I think so, but it’s my opinion,” Zelenskyy said.

The U.S. and global allies unveiled new security commitments for Ukraine, and reassured Kyiv has a place in the treaty organization after the war is over and after certain reforms are implemented.

Zelenskyy also singled out the aid provided by the U.S., thanking Biden for his decision last week to send controversial cluster munitions to Ukraine as it continues its counteroffensive against Russia.

Biden praised Zelenskyy and Ukraine for their “resilience and resolve” and said he looks forward to the day they can celebrate their official entry into NATO.

When ABC News asked Zelenskyy how soon Ukraine would like to join the alliance after the conflict ends, Biden offered a sarcastic response of “an hour and 20 minutes.”

Biden secured a major foreign policy win earlier this week when Turkey agreed to back Sweden’s bid to join the alliance, a sudden reversal more than a year after the Nordic nation applied for membership.

The president strongly pushed for Sweden’s entry, and lauded the agreement reached between Prime Minister Ulf Kristersson and Turkey’s President Recep Tayyip Erdogan on the eve of the summit. Questions have been raised about how much of a role the U.S. played in the agreement, as the administration announced Tuesday it is moving ahead with the potential sale of American F-16 fighter jets to Ankara.

Following his speech in Lithuania’s capital, Biden will travel to Helsinki, Finland for a U.S.-Nordic Leaders Summit. There, he will celebrate Finland becoming the newest member of the NATO alliance.

ABC News’ Justin Gomez and Cheyenne Haslett contributed to this report.

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