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!"

An in-person meeting between Ukrainian President Volodymyr Zelenskyy and U.S. President Joe Biden is currently underway in Lithuania's capital.

Zelenskyy took to Twitter on Wednesday evening to announce that their bilateral meeting in Vilnius "has begun." It's the third face-to-face meeting to take place between the two leaders this year.

"The focus is on security and everything that enhances it," Zelenskyy tweeted. "It will be meaningful."

Russian President Vladimir Putin has been briefed by the country's security agencies about what was referred to as an "attempted armed rebellion," according to Russia's state-run media.

The late-night statement from Putin's spokesman suggested that the Kremlin considered Wagner Group's move into Rostov-on-Don, a key Russian city close to the border with Ukraine, to be a "rebellion."

Wagner's founder Yevgeny Prigozhin in an audio message on Friday claimed his forces would now punish Russia's defense minister and chief of general staff, telling other units to stand down and not offer resistance.

"Special services, law enforcement agencies, namely the Ministry of Defense, the FSB, the Ministry of Internal Affairs, Rosgvardiya, in round-the-clock mode, constantly report to the president on the measures taken in the context of the implementation of the instructions previously given to him," Kremlin spokesperson Dmitry Peskov said on Saturday.

-ABC News' Tanya Stukalova and Patrick Reevell