Senior congressional leaders were briefed about the ongoing situation in Russia, according to a congressional aide.

U.S. intelligence officials told the so-called "Gang of Eight" -- the top Republicans and Democrats currently in congressional leadership-- in recent days about potentially concerning movements of Wagner Group forces and equipment build-ups near Russia. However, it was unclear to U.S. intelligence what was going to happen and when.

-ABC News' Trish Turner

A senior U.S. official says it is a mystery as to why Yevgeny Prigozhin stopped his march to Moscow given that he was seemingly in a dominant position.

The official said he was greeted as a hero in Rostov-on-Don. However, the senior official told ABC News that Prigozhin is in an "emotional state," and perhaps did it because he thought this would destroy Russia, or because he glimpsed his own end. It is impossible to tell whether Prigozhin thinks Russian President Vladimir Putin will actually honor their deal which included allowing Wagner group soldiers to be folded into the Russian military.

The official said that Belarus President Alexander Lukashenko was very effective, telling Prigozhin and Putin that this was all a misunderstanding and that they are both patriots and aligned for the same goals.

Putin is said to be completely shocked by how fast Wagner Group moved through Russia. For now, he is just trying to secure his position. He does not want to be seen negotiating over his defense minister, but the official says the U.S. believes concessions were made over Sergei Shoigu's future as well as others.

-ABC News' Martha Raddatz

Secretary of State Antony Blinken spoke Saturday with Turkish Foreign Minister Hakan Fidan to discuss the ongoing situation in Russia.

"Secretary Blinken reiterated that U.S. support for Ukraine will not change. The United States will stay in close coordination with Allies and partners as the situation develops," spokesperson Matthew Miller said.

Blinken also spoke with Ukrainian Foreign Minister Dmytro Kuleba on Saturday to discuss the situation in Russia, Miller said. Blinken reiterated that support by the U.S. for Ukraine will not change.

The U.S. will stay in close coordination with Ukraine as the situation develops.

-ABC News Shannon K. Crawford

Yevgeny Prigozhin will go to Belarus to ease tensions and the fighters of PMC Wagner Group who took part in the so-called "campaign" against Moscow will not be prosecuted, the Kremlin said Saturday evening.

The rest will be able to sign a contract with the Ministry of Defense, the President of the Russian Federation Dmitry Peskov told reporters.

"In the end, we managed to resolve this situation without further losses, without raising the level of tension," Peskov said.

"An agreement was reached that PMC Wagner would return to their camps," he added.

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