Yevgeny Prigozhin, the 62-year-old head of the Wagner mercenary group, has vowed to “go to the end” to topple Russia’s military leadership, whom he accuses of launching deadly missile strikes on his forces. In an audio message, he said: “We will destroy everything that stands in our way.” Prigozhin, who has a criminal past, has made the most audacious challenge to President Vladimir Putin since the start of the offensive in Ukraine last year. He has also claimed his forces shot down a Russian military helicopter and has called on Russians to join him, saying “there are 25,000 of us.”

In Moscow, authorities have tightened security measures, with the FSB security service urging Wagner fighters to “take measures to detain” Prigozhin. Prosecutor General Igor Krasnov has informed Mr. Putin of “the initiation of a criminal case in connection with an attempt to organise an armed rebellion.” Prigozhin has continued to blame the Defence Minister Sergei Shoigu and Valery Gerasimov, chief of the general staff, for his fighters’ deaths, saying: “The council of commanders of PMC Wagner has made a decision - the evil that the military leadership of the country brings must be stopped.” The Russian defence ministry has denied Prigozhin’s claims of an attack on his forces, calling them a “provocation”.It later said Ukrainian troops were taking advantage of the infighting to ready an assault near the east Ukraine hotspot of Bakhmut. Sergei Surovikin, commander of Russia’s aerospace forces, urged Prigozhin to call off efforts to remove the leadership of Moscow’s defence ministry.

Ukraine was also on high alert after new Russian missile strikes Saturday, with explosions reported in Kyiv and the eastern city of Kharkiv. U.S. President Joe Biden had been briefed on the situation in Russia, and Kyiv said it was monitoring the infighting in Moscow. After years of operating in the shadows, Prigozhin has now admitted to running the enigmatic Wagner mercenary group and even interfering in U.S. elections. He has also claimed Moscow’s forces were retreating in Ukraine’s east and south, something that directly contradicts Mr. Putin’s account. Rarely has such a controversial figure shot to this degree of prominence on the Russian political stage under Mr. Putin. Prigozhin rose from a modest background to become part of the inner circle around Mr. Putin, and his forces played a central role in Russia’s capture of the town of Bakhmut in the eastern region of Donetsk. He now questions the military operation, saying: “The war was needed for the self-promotion of a bunch of bastards.”