The NATO summit in Vilnius showed that the NATO "alliance has finally returned to the schemes of the Cold War," the Russian Foreign Ministry said in a statement Wednesday.

"NATO consistently lowers the threshold for the use of force and strengthens the nuclear component in military planning," the statement added.

The Russian Foreign Ministry also noted NATO countries "promised to continue supplying more and more long-range weapons to Kyiv," saying they are doing so in order to "prolong the conflict."

-ABC News' Tanya Stukalova

Ukrainian President Volodymyr Zelenskyy said he received assurances that Ukraine will become a member of NATO and told reporters he believes it will happen "as soon as the security situation is stabilized," when answering questions after the conclusion of the NATO summit in Vilnius, Lithuania, on Wednesday.

When asked what Zelenskyy got out of the summit, he said he received "support from the leaders and an unambiguous statement that Ukraine will be in NATO."

"I believe that we will be in NATO as soon as the security situation is stabilized. In simple terms, the moment the war is over, Ukraine will definitely be invited to join NATO and Ukraine will definitely become a member of the alliance. I have not heard any other opinion today," Zelenskyy said.

-ABC News' Ellie Kaufman

Wagner forces are turning over weapons and military equipment to the Russian Armed Forces, the country's defense ministry said Wednesday.

More than 2,000 pieces of equipment and weapons were transferred to the Russian Armed Forces from Wagner forces, including hundreds of tanks, air defense systems, self-propelled artillery mounts, armored personnel carriers and more, the defense ministry said.

Among the equipment, dozens of units have never been used in combat before.

Russian forces also received more than 2,500 tons of various ammunition and about 20,000 small arms, the defense ministry said.

Separately, the Belarusian Interior Ministry has "begun talks seeking to invite Wagner Group members to train its troops," Interfax, a Russian news agency, reported Wednesday.

-ABC News' Ellie Kaufman

Ukrainian President Volodymyr Zelenskyy said his in-person meeting with U.S. President Joe Biden in Lithuania’s capital on Wednesday was "very good" and "powerful."

Zelenskyy took to Twitter after their meeting ended in Vilnius, saying it lasted "twice as long as planned" and "was as meaningful as it needed to be."

"If the protocol had not stopped the meeting, we would have talked even longer," he tweeted.

Zelenskyy said their meeting covered "all the topics," including long-term support for Ukraine, weapons, politics and NATO membership.

"We clearly see how to end this war with our common victory," he added. "Thank you, Mr. President!"

The Kremlin on Wednesday acknowledged for the first time that a plane carrying Yevgeny Prigozhin, mercenary chief of the paramilitary Wagner Group, was possibly downed on purpose.

Kremlin spokesman Dmitry Peskov told reporters that investigators are looking into the possibility that the 62-year-old Prigozhin was assassinated.

"It is obvious that different versions are being considered, including the version -- you know what we are talking about -- let's say, a deliberate atrocity," Peskov said when asked about the investigation.

The plane carrying Prigozhin and nine others crashed in Russia's Tver region on Aug. 23, killing everyone aboard, according to the press service of Russia's Federal Air Transport Agency.

The crash came about a month after Prigozhin led a chaotic armed rebellion that threatened the longstanding leadership of Russian President Vladimir Putin.

On Friday, Peskov denied speculation that the Kremlin was involved in the plane crash, calling the allegation an "absolute lie."

The crash investigation is being conducted by the Russian Investigative Committee as a domestic incident and Peskov said that allowing in international investigators "is out of the question."

-ABC News' Will Gretsky