The governor of Russia's Lipetsk province said Saturday that the Wagner mercenary group has entered the region.

The Lipetsk region is about 360 kilometers (225 miles) south of Moscow and much farther toward the capital than Rostov-on-Don, where Wagner forces appeared during the night.

Authorities "are taking all necessary measures to ensure the safety of the population. The situation is under control," Gov. Igor Artamonov said on Telegram. He did not give details about the Wagner presence.

The owner of the Wagner Group, a private mercenary army, made his most direct challenge to the Kremlin yet on Friday, calling for an armed rebellion aimed at ousting Russia's defense minister. The security services reacted immediately by calling for the arrest of its leader, Yevgeny Prigozhin.

In a sign of how seriously the Kremlin was taking the threat, security was heightened in Moscow and in Rostov-on-Don, which is home to the Russian military headquarters for the southern region and also oversees the fighting in Ukraine.

While the outcome of the confrontation was still unclear, it appeared likely to further hinder Moscow's war effort as Kyiv's forces were probing Russian defenses in the initial stages of a counteroffensive.

Prigozhin claimed early Saturday that his forces had crossed into Russia from Ukraine and had reached Rostov, saying they faced no resistance from young conscripts at checkpoints and that his forces "aren't fighting against children."

"But we will destroy anyone who stands in our way," he said in one of a series of angry video and audio recordings posted on social media beginning late Friday. "We are moving forward and will go until the end."

 

He claimed that the chief of the General Staff, Gen. Valery Gerasimov, scrambled warplanes to strike Wagner's convoys, which were driving alongside ordinary vehicles. Prigozhin also said his forces shot down a Russian military helicopter that fired on a civilian convoy, but there was no independent confirmation.

"We are monitoring the situation and will be consulting with allies and partners on these developments," U.S. National Security Council spokesperson Adam Hodge told CBS News in a statement. Hodge added that President Biden had been briefed on the situation. 

"We are closely monitoring what appears to be a significant internal conflict among Russian forces," Sens. Mark Warner and Marco Rubio, the respective chair and vice chair of the Senate Intelligence Committee, said in a statement. "We are in touch with the Intelligence Community and Administration as this situation unfolds." 

According to CBS News correspondent Ian Lee, the Kremlin tightened security at key facilities around the country overnight.  Moscow woke up to a state of emergency, and Putin has ordered anti-terror measures in several regions, giving law enforcement broad legal powers. 

Lee also reported that there are reports that Wagner troops have seized a second city halfway to Moscow.  

And despite Prigozhin's statements that Wagner convoys had entered Rostov-on-Don, there was no confirmation of that yet on Russian social networks. Videos showed heavy trucks blocking highways leading to the city, long convoys of National Guard trucks were seen on a road outside Rostov-on-Don and armored vehicles were roaming the streets.

Prigozhin said Wagner field camps in Ukraine were struck by rockets, helicopter gunships and artillery fire on orders from Gerasimov following a meeting with Defense Minister Sergei Shoigu, at which they decided to destroy Wagner.

Prigozhin on Friday called for an armed rebellion aimed at ousting Shoigu. The security services reacted immediately by opening a criminal investigation into Prigozhin.

Prigozhin posted a series of angry video and audio recordings in which he accused Shoigu of ordering a rocket strike Friday on Wagner's field camps in Ukraine, where his troops are fighting on behalf of Russia.

Prigozhin said his troops would now punish Shoigu in an armed rebellion and urged the army not to offer resistance.

"This is not a military coup, but a march of justice," Prigozhin declared.

The National Anti-Terrorism Committee, which is part of the Federal Security Services, said he would be investigated on charges of calling for an armed rebellion. The state news agency Tass said President Vladimir Putin was kept informed.

Kremlin spokesperson Dmitry Peskov later said that Igor Krasnov, Russia's prosecutor general, has spoken to Putin about the possibility of initiating a criminal case against Prigozhin, according to Tass. 

Wagner's forces have played a crucial role in Russia's war in Ukraine, succeeding in taking the city where the bloodiest and longest battles have taken place, Bakhmut. Prigozhin has frequently criticized Russia's military brass, accusing it of incompetence and of starving his troops of weapons and ammunition, but his accusations and calls for armed rebellion Friday were a more direct challenge.

The Russian Defense Ministry required all military contractors to sign contracts with it before July 1, but Prigozhin, whose feud with the Defense Ministry dates back years, refused to comply.

In a statement issued late Friday, he said he was ready to find a compromise with the Defense Ministry, but "they have treacherously cheated us."

"Today they carried out a rocket strike on our rear camps, and a huge number of our comrades got killed," he said.

Prigozhin claimed that Shoigu went to the Russian military headquarters in the southern city of Rostov-on-Don personally to direct the strike on Wagner and then "cowardly" fled.

"This scum will be stopped," he said, in reference to Shoigu.

"The evil embodied by the country's military leadership must be stopped," he shouted, urging the army not to offer any resistance to Wagner as it moves to "restore justice."

In other developments in the Ukraine, war, Ukrainian President Volodymyr Zelenskyy called on other countries to heed warnings that Russia may be planning to attack an occupied nuclear power plant to cause a radiation disaster.

Members of his government briefed international representatives on the possible threat to the Zaporizhzhia Nuclear Power Plant, whose six reactors have been shut down for months. Zelenskyy said that he expected other nations to "give appropriate signals and exert pressure" on Moscow.

"Our principle is simple: The world must know what the occupier is preparing. Everyone who knows must act," Zelenskyy said late Thursday. "The world has enough power to prevent any radiation incidents, let alone a radiation catastrophe."

The Kremlin's spokesman has denied the threat to the plant is coming from Russian forces.

The potential for a life-threatening release of radiation has been a concern since Russian troops invaded Ukraine last year and seized the plant, Europe's largest nuclear power station. The head of the U.N.'s atomic energy agency spent months trying to negotiate the establishment of a safety perimeter to protect the facility as nearby areas came under repeated shelling, but he has been unsuccessful.

The International Atomic Energy Agency noted Thursday that "the military situation has become increasingly tense" while a Ukrainian counteroffensive that got underway this month unfolds in Zaporizhzhia province, where the namesake plant is located, and in an adjacent part of Donetsk province.

Although the last of the plant's six reactors were shut down last fall to reduce the risk of a meltdown, experts have warned that a radiation release could still happen if the system that keeps the reactors' cores and spent nuclear fuel cool loses power or water.

During months of fighting, Russia and Ukraine have traded blame over which side was increasing the threat to the plant. On Friday, IAEA Director-General Rafael Mariano Grossi met with the head of the Russian state nuclear corporation Rosatom in the Kaliningrad exclave of Russia to discuss the conditions at the plant. Rosatom director Alexey Likachev and other officials "emphasized that they now expect specific steps" from the U.N. agency to prevent Ukrainian attacks on the plant and its adjacent territory, said a statement from the Russian corporation, whose divisions build and operate nuclear power plants.

Earlier this week, Ukrainian officials accused Russia of mining the plant's cooling system, already under threat from a dam collapse earlier this week that drew down water in a reservoir that the power station uses.

Elsewhere in the southern Zaporizhzhia province, Gov. Yuriy Malashko reported Friday that Russian shelling killed two people in the past day. And in the Kherson province, a Russian attack that hit a transportation company in the capital killed three people, Gov. Oleksandr Prokudin said.

Russia also fired 13 cruise missiles overnight at a military airfield in the western Khmelnytskyi province, but Ukrainian air defenses intercepted them all, according to the air force. The attack came after Russia-appointed officials said that Ukrainian-fired missiles damaged a bridge that serves as a key supply link to occupied areas of southern Ukraine. Photos showed that the Russians had erected a pontoon bridge as a bypass. Ukrainian authorities reported striking Russian soldiers holed up in a nearby former wine factory in Henichesk. Russia's state news agency Tass reported two were killed in the attack.

Russia's air-launched Kh-101 and Kh-555 missiles were sent from the Caspian Sea, the air force said. It didn't identify the targeted airfield, but Ukraine has an air base near the Khmelnytskyi region's town of Starokostiantyniv.

The base houses fighter jets and bombers, and five years ago hosted a training exercise with air force personnel from the United States, Ukraine and seven European countries. It has come under Russian attack previously, including within the last month.

Ukrainian Deputy Defense Minister Hanna Maliar said Friday that Russia has beefed up its defense forces in southern Ukraine in response to the early counteroffensive and intensified its efforts to take more ground in the east. Asked if the Ukrainian military's initial attacks set the stage for a larger assault, Maliar told Ukrainian television: "We are yet to see the main events, and the main blow. And indeed, a part of reserves will be used later."

Ukrainian forces so far have made only incremental gains in Zaporizhzhia province, one of four regions that Russian President Vladimir Putin illegally annexed last year. Putin has pledged to defend the regions as Russian territory.

Zelenskyy has said that Ukraine is fighting to force Russian troops out of those regions, as well as the Crimean Peninsula, which Moscow illegally annexed in 2014 and is using as a staging and supply route in the 16-month-old war. If the counteroffensive breaks the Russian defenses in the south, Ukrainian forces could attempt to reach a pair of occupied port cities on the Sea of Azov and break Russia's land bridge to Crimea.

In:
• Ukraine
• Russia
• Vladimir Putin
• Volodymyr Zelenskyy