President Volodymyr Zelenskyy again called on Tuesday for NATO to invite Ukraine to become a member, offering a strongly worded statement as the coalition leaders gathered for a summit in Lithuania.

Ukraine "deserves respect," Zelenskyy said in a statement posted on Twitter.

"It's unprecedented and absurd when time frame is not set neither for the invitation nor for Ukraine's membership," he said. "While at the same time vague wording about 'conditions' is added even for inviting Ukraine. It seems there is no readiness neither to invite Ukraine to NATO nor to make it a member of the Alliance."

Keeping Ukraine out of NATO amounts to a "motivation" for Russia to "continue its terror," he said.

"Uncertainty is weakness," he added.

Russia rebutted the statement a short while later.

"This is potentially very dangerous for European security. Indeed, it is fraught with great dangers, and those who will make this decision should be aware of that," Dmitry Peskov, a Kremlin spokesperson, said when asked to comment on Ukraine's possible fast-track admission to the coalition.

President Joe Biden will meet with Ukrainian President Volodymyr Zelenskyy at the NATO summit in Vilnius, Lithuania this week, an administration official told ABC News.

The meeting comes as Zelenskyy pushes for a spot in NATO, despite Biden's public comments this weekend that he doesn't think that's the right move at this moment.

Biden has instead suggested a relationship similar to Israel and the U.S., with strong security commitments.

-ABC News' Cheyenne Haslett and Molly Nagle

Turkey and Sweden have reached a deal to advance the latter country's bid to join NATO, according to NATO Chief Jens Stoltenberg.

"This is an historic step which makes all #NATO Allies stronger & safer," Stoltenberg tweeted along with a photo of him and the two leaders shaking hands.

Turkey and Sweden have agreed to work on "legitimate security concerns," according to NATO.

Sweden has resumed arms exports with Turkey and "will present a roadmap as the basis of its continued fight against terrorism in all its forms and manifestations," according to NATO.

The two countries agreed to set up economic cooperation through the Türkiye-Sweden Joint Economic and Trade Committee, NATO said.

-ABC News' Will Gretsky

Ukrainian President Volodymyr Zelenskyy outlined his agenda for the NATO summit in Vilnius in his evening address.

Zelenskyy said the Ukrainian government is "working to make the algorithm for gaining membership as clear and fast as possible."

The president also added, in regards to the summit, "there may be good weaponry-related news."

"The priorities are absolutely clear: air defense for our cities, for all communities throughout the country, we are working to create a full-fledged sky shield," he said.

-ABC News' Will Gretsky

The United States is standing by the NATO communique released Tuesday and its language around Ukraine joining the alliance, despite criticism from Ukrainian President Volodymyr Zelenskyy over the lack of a timeline to do so.

"The United States clearly joined with NATO allies in agreeing to a strong positive message reaffirming that Ukraine will become a member of the alliance," U.S. National Security Council Senior Director for Europe Amanda Sloat said during a press briefing in Lithuania's capital on Wednesday morning, on the final day of a high-stakes NATO summit. "And as the communique has made clear, as the president has spoken to directly in the past, we recognize that Ukraine has already made significant progress in terms of reforms. That was part of what led to allies making the decision to say that the Membership Action Plan was no longer required for Ukraine."

"But as both the president has said and as the communique made clear, there is still the need for Ukraine to take further democratic and security sector reforms," she added.

Sloat told reporters that the U.S. has been and would continue to work with Ukraine both bilaterally and through the NATO alliance to ensure that the reforms required to join the alliance are met.

When asked to respond to Zelenskyy's criticism that the lack of a timeline was "unprecedented and absurd," Sloat defended the agreement as a significant one.

"I would agree that the communique is unprecedented, but I see that in a positive way. We joined with allies yesterday in agreeing to a very strong, positive message. We reaffirmed that Ukraine will become a member of the NATO alliance," she said, arguing that removing the Membership Action Plan requirement for Ukraine was a "very significant" step on NATO's part.

-ABC News' Molly Nagle