The plane belonging to Russian President Vladimir Putin departed from Moscow to St. Petersburg early Saturday as the Kremlin attempts to quiet an “armed rebellion” from Wagner mercenaries threatening to weaken the country’s offensive in the Ukrainian war.

The departure comes just hours after mercenary chief Yevgeny Prigozhin led his troops out of Ukraine and into a key city south of Moscow, marking the biggest threat to Putin’s leadership in over two decades in power. Putin responded to the move on Friday, calling the uprising "a stab in the back.”

Ukrainian President Volodymr Zelensky responded to the internal rebellion on Saturday, criticizing the "stupidity” of Russia’s government and claiming its “weakness” has been exposed by the uprising.

The revolt comes after Prigozhin accused the Russian military of attacking his Wagner military forces, vowing to retaliate against the Kremlin. In a speech to supporters on Friday, Putin called the uprising a "betrayal" and "treason."

"All those who prepared the rebellion will suffer inevitable punishment," Putin said. "The armed forces and other government agencies have received the necessary orders."

However, Prigozhin has described himself as a patriot.

"Regarding the betrayal of the motherland, the president was deeply mistaken,” he said in an audio message on his Telegram channel. “We are patriots of our homeland.”

The Wagner forces have played a key role in the Russian offensive of the Ukrainian war by capturing the eastern city of Bakhmut, where the bloodiest and longest battles have taken place. But Prigozhin has increasingly criticized the military brass, accusing it of incompetence and of starving his troops of munitions.