Wagner Group leader Yevgency Prigozhin was "likely" killed in a plane crash near Kuzhenkino, Russia, on Wednesday, the Pentagon said.

Pentagon press secretary Brig. Gen. Pat Ryder said there is no information to suggest a surface-to-air missile brought down the plane. Nine others, including Wagner's co-founder, Dmitry Utkin, are also presumed dead.

"We don't have any information to indicate right now ... there was some type of surface to air missile that took down the plane ... we assessed that information to be inaccurate," Ryder said.

He added, "But beyond that, I'm really just not going to have any further information. What was it, something that came ... from inside the plane? Again, I don't have any additional insight to provide on that."

-ABC News’ Luis Martinez

Russian President Vladimir Putin offered his first comments Thursday on the plane crash that presumably killed Wagner Group head Yevgeny Prigozhin and the private military company's co-founder Dmitry Utkin along with eight others near Kuzhenkino, Russia, on Wednesday.

"As for the aviation tragedy, first of all, I want to express my sincerest condolences to the families of all the victims," Putin said in an on-camera address, adding that Wagner Group made a "significant contribution to our common cause of fighting the neo-Nazi regime in Ukraine."

"I knew (Yevgeny) Prigozhin for a very long time, since the early 1990s. He was a man with a complex destiny, and he made serious mistakes in life," Putin said. "He achieved the results he needed both for himself and, when I asked him, for the common cause, as in these last months."

Putin said of the investigation, "But what is absolutely clear -- the head of the Investigative Committee reported to me this morning, they have already launched a preliminary investigation into this incident. And it will be carried out in full and to the end. There is no doubt about that here. Let's see what the investigators say in the near future. Tests -- technical and genetic tests -- are being carried out now. This takes some time."

-ABC News’ Will Gretsky

Mercenaries with the Russian private military company Wagner Group were observed leaving Belarus where the group’s forces had set up camp since a failed rebellion against Russian military leaders in June, according to Andrii Demchenko, a spokesman for Ukraine’s State Border Guard Service.

The group’s movements were observed by Ukrainian border guards and intelligence officials, Demchenko said Thursday.

The reported exit comes a day after Wagner leader Yvegeny Prigozhin and the group’s co-founder and operations manager Dmitry Utkin were presumed to have died in a plane crash near Moscow.

-ABC News’ Will Gretsky

Ukrainian troops have landed in occupied Crimea, a state defense official said on Thursday.

The landing in territory long held by Russian forces was accomplished without Ukrainian casualties, Andriy Yusov, spokesperson for the Defense Ministry, said on Telegram. Russian forces suffered personnel losses, he said.

Russia illegally annexed Crimea from Ukraine in 2014.

-ABC News’ Joe Simonetti

Ukrainian President Volodymyr Zelenskyy and U.S. President Joe Biden are set to meet in Lithuania’s capital on Wednesday afternoon, a day after NATO leaders announced during a summit that Ukraine will be allowed to join the alliance "when allies agree and conditions are met" but didn't offer a timeline.

Earlier Wednesday, Zelenskyy held a joint press conference with NATO Secretary-General Jens Stoltenberg, fielding many questions from reporters about Ukraine's path to NATO membership. The Ukrainian president took a noticeably softer tone compared to his remarks the previous day criticizing the lack of a timeline as "unprecedented and absurd."

Zelenskyy told reporters it's difficult as NATO partners are living under different conditions, whereas in Ukraine "survival" matters. He said he understands some people are "afraid" to talk about Ukraine joining NATO because "nobody is willing to have a world war." He acknowledged that his country cannot be a member of the alliance while a war is going on within its borders, but he said "signals are important."

When asked about his upcoming meeting with Biden and how he plans to convince the U.S. president that Ukraine is ready for NATO membership, Zelenskyy responded with gratitude to the United States and confidence that Ukraine will join the alliance once Russia's war is over.

"I'm grateful to President Biden and to the Congress and to the people of United States that are truly the leaders in support and assistance to Ukraine. We highly appreciate this," the Ukrainian president told reporters. "Not planning to find any arguments for making sure that President Biden would see us in NATO. I believe that those arguments, they should be mutual because it's all about this security, the East, the European continent, the Eastern Flank of NATO. And I believe that NATO needs us just as we need NATO. And I believe that this is absolutely fair. I am confident that after the war, Ukraine will be in NATO. We will be doing everything possible to make it happen so that we with the United States would have a same understanding and same vision."

-ABC News' Molly Nagle and Joe Simonetti