Happening now.

President Biden vows the United States and the NATO allies will not waver in their

support of Ukraine.

Their critical summit here in Lithuania ending with a strong show of unity, despite unanswered

questions about when Ukraine will be invited to join the NATO alliance.

Also tonight, President of Lodemir Zelenski. He returns to Ukraine with

new assurances from Western Allies and face-to-face commitments for President Biden.

But Zelenski leaves the summit without concrete

security guarantees or a timeline for NATO membership. We're watching all of

this unfold right now here in the situation room. What does it all mean for Ukraine's defense against Russia's brutal war?

I'll ask the Ukrainian ambassador to the United States

who's joining us live this hour.

We want to welcome our viewers in the United States and

around the world. I'm Wolflitzer in Vilnius, Lithuania, and you're in the

situation room. We're live here in Vilnius, the capital of Lithuania, and the backdrop for a truly momentous summit

for President Biden and the NATO alliance.

NATO leaders offering the Ukrainian president

Lodimir Zelensky

just enough to ease his frustrations and to soften his very public criticism.

But tonight, Zelensky still doesn't have a definite roadmap to reach his goal of NATO membership for Ukraine.

Let's begin with our White House correspondent Arlet's sign.

She's already in Helsinki, Finland where President Biden landed just a little while ago.

...