The Biden administration on Monday said it doesn't know Wagner Group chief Yevgeny Prigozhin's whereabouts, including which country he is in, following his short-lived rebellion against Russian President Vladimir Putin. 

State Department spokesman Matt Miller confirmed as much during a news briefing, adding that it was a "new thing to see President Putin's leadership directly challenged" amid Moscow's invasion of Ukraine. 

Prigozhin shocked the world this weekend when he turned his private military group against Russian forces, while taking control of Russian military bases. He relented on Saturday after Belarus held negotiations between the two sides.

The Kremlin said it made a deal in which the mercenary chief will move to Belarus and he and his soldiers will receive amnesty. 

WHAT DOES PUTIN'S STANDOFF WITH WAGNER MERCENARY GROUP MEAN FOR RUSSIA?

Prigozhin speaks in video address

Yevgeny Prigozhin, the owner of the Wagner Group military company, records his video addresses in Rostov-on-Don, Russia, Saturday, June 24, 2023. The owner of the Wagner private military contractor who called for an armed rebellion aimed at ousting Russia's defense minister has confirmed in a video that he and his troops have reached Rostov-on-Don.  (Prigozhin Press Service via AP)

"I don't have any assessment about his location," Miller said of Prigozhin. "This certainly was a new moment."

On Monday, Prigozhin posted an 11-minute voice recording on social media outlining his reasons for going against Putin as his forces headed toward Moscow before an abrupt halt. 

The march toward Moscow was intended to be a protest against the prosecution of the war in Ukraine and not aimed at regime change in Russia, he said, according to a Reuters translation. 

INNER WORKINGS OF WAGNER MERCENARY GROUP REVEALED AMID CALL TO ADD ORGANIZATION TO US TERROR LIST

"We started our march due to injustice. We showed no aggression, but we were hit by missiles and helicopters. This was the trigger," the warlord said in the recording.

Prior to his revolt, Prigozhin had criticized Russian military leaders, including Defense Minister Sergei Shoigu and Chief of the General Staff Valery Gerasimov, for failing to provide his troops with enough ammunition during the bloody battle of Bakhmut. 

Wagner group rebellion

Members of Wagner group inspect a car in a street of Rostov-on-Don, on June 24, 2023. President Vladimir Putin on June 24, 2023, said an armed mutiny by Wagner mercenaries was a "stab in the back" and that the group's chief Yevgeny Prigozhin had betrayed Russia, as he vowed to punish the dissidents. Prigozhin said his fighters control key military sites in the southern city of Rostov-on-Don. (STRINGER/AFP via Getty Images)

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Miller said the conflict between Putin and his former ally is an internal Russian affair "in which the United States is not involved and will not the involved." He added that the U.S. does not take a position as to who leads Russia.

"We want a Russia that is not invading its neighbors and not trying to violate the territorial sovereignty of its neighbors," Miller said. 

He noted that Wagner forces have committed numerous human rights violations and generally bring destruction and chaos in any country the group operates in. 

Fox News' Anders Hagstrom contributed to his report.