Wagner leader Yevgeny Prigozhin said his forces won’t surrender after Russian President Vladimir Putin denounced their military rebellion as “treason” in a crisis that’s rapidly spiraling into the most serious threat to the Kremlin leader’s authority in decades.

The insurrection is without precedent in Putin’s nearly quarter-century rule in Russia, jolting a country simultaneously trying to sustain a war in Ukraine that’s the biggest conflict in Europe since World War II. It’s unfolding against the backdrop of a Ukrainian counteroffensive across some of the area where Wagner’s mercenaries deployed for months in the war’s longest and bloodiest battle.

In a televised address to the nation Saturday, Putin said those who “organized and prepared a military mutiny, who took up arms against their comrades, betrayed Russia and will answer for it.” He threatened “harsh” retaliation, calling the uprising “a stab in the back” for the country amid the war.

Putin is “deeply mistaken” to attack Wagner and “nobody is going to turn himself in at the request of the president,” Prigozhin said in an audio post on Telegram. His troops were “patriots” who answered the Kremlin’s call to join the war in Ukraine and don’t want Russia “to continue living in corruption, deception and bureaucracy,” he said.

The question now is whether Prigozhin is able to capitalize on his momentum or whether the revolt fizzles out as the Kremlin strives to gain the upper hand.

While Putin has the support of Russia’s military hierarchy, it’s difficult to assess the response of the army’s lower ranks, Tatyana Stanovaya, founder of R.Politik, a political consulting firm, said on Telegram. “If orders to open fire are issued, how will individual soldiers react?” she said.

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The US and Europe were closely monitoring the dramatic escalation in a long-running feud between the powerful mercenary leader and Russia’s defense establishment over the faltering invasion. Previously seen as loyal to Putin, Prigozhin has vowed to march on Moscow after accusing the Defense Ministry of covering up “enormous” Russian casualties, a direct challenge to the president who has stood by his army chiefs.

Ukrainian President Volodymyr Zelenskiy said the crisis exposed Russia’s “full-scale weakness.”

Prigozhin posted a video of himself earlier Saturday at what he said were military offices in the southern Russian city of Rostov-on-Don that were under Wagner’s control along with the local airfield. The claims couldn’t be independently confirmed.

Videos on social media also showed military helicopters flying over the city of Voronezh where a fuel storage depot was rocked by an explosion. Regional Governor Alexander Gusev said the depot was on fire, without giving an explanation.

Officials announced a “counter-terrorist regime” in Moscow and its surrounding region as well as in Voronezh region, which lies along the main road about midway from Rostov-on-Don to the capital. Prigozhin has said his troops would head to Moscow from Rostov.

“We are all ready to die,” he said in a separate audio message, claiming Wagner had 25,000 troops involved and another 25,000 who were ready to join.

‘Excessive Ambitions’

Putin didn’t name Prigozhin during his five-minute broadcast in which he said “excessive ambitions and personal interests led to treason” against the state and “the cause for which Wagner fighters and commanders fought and died.” He drew a comparison with divisions in Russia during World War I that led to the 1917 Bolshevik revolution and civil war.

The Kremlin was taking no chances. Security in the capital was tightened including around government buildings, and riot police were put on alert, state-run Tass news service reported. Russia opened a criminal case against Prigozhin and the Federal Security Service said it was seeking to detain him.

Putin discussed the situation by phone with Turkish President Recep Tayyip Erdogan, who expressed “complete support” for the Russian authorities, the Kremlin said in a statement.

The Russian leader also held phone talks with his ally, Belarus President Alexander Lukashenko, the state-run Belta news service reported. Putin spoke by phone, too, with his Kazakh counterpart Kassym-Jomart Tokayev, the Kazakh leader’s press service said.

In Washington, President Joe Biden was briefed on the situation. A European Union spokesman said it was “carefully” monitoring developments, while the UK Defence Ministry called the rebellion “the most significant challenge to the Russian state in recent times” in its latest intelligence update.

Risks Ahead

While Prigozhin has become a liability for the Russian military, there are risks for Russia if he is replaced, according to a US official. There is nobody as effective as him waiting in the wings and the Russian military would face the difficult task of managing a disparate group of mercenaries that includes criminals if Prigozhin is removed, the official said.

The German government was taken completely by surprise. A senior government official on Friday shared the assumption that Prigozhin was acting on Putin’s behalf, with even the Wagner leader’s violent outbursts against Defense Minister Sergei Shoigu seen as part of the president’s larger plan of cementing his power by letting his military leaders fight among themselves.

The Russian Defense Ministry on Saturday issued an appeal to Wagner fighters to abandon the revolt, saying they had been “deceived into Prigozhin’s criminal adventure” in a statement read out on state television. “Many of your comrades from several detachments have already realized their mistake” and turned themselves over to law-enforcement, it said.

Long-Brewing Feud

Prigozhin, 62, has for months attacked Shoigu and top army officials in Moscow, alleging they failed to adequately support Wagner forces fighting in Ukraine, particularly during battles for the eastern Ukrainian city of Bakhmut.

He has also repeatedly called for the authorities to introduce tougher measures including full mobilization and martial law to prosecute the war in Ukraine, warning that Russia risked defeat without them.

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Putin had long appeared to tolerate the mercenary’s outbursts, relying on his troops to fight in key parts of the front. But his high profile rankled the military brass, which regularly sought to undermine and sideline him.

Tensions erupted Friday when Prigozhin posted a series of audio messages on his Telegram channel vowing to “punish” Russia’s military leaders for what he alleged was a missile attack on a Wagner base and the losses of “tens of thousands” of Russian troops in the war.

He accused Shoigu of overseeing an operation to “destroy” Wagner. The Defense Ministry denied Prigozhin’s claims about a strike.

Frictions had been rising again in recent weeks after Shoigu set a July 1 deadline for all volunteer units to sign a formal contract with the Defense Ministry — an order Prigozhin bluntly rejected. Putin backed the ministry’s demand during a meeting with Russian journalists and military bloggers last week.

Earlier Friday, the Wagner leader posted a video on Telegram accusing the Defense Ministry of “deceiving” Russians and Putin about the war as he challenged Kremlin justifications for the February 2022 invasion of Ukraine.