<div><span style="font-size: 1rem;"><b>Rebel mercenaries advanced north towards Moscow after seizing a key military base Saturday, just as Kremlin chief Vladimir Putin's vowed to defeat the revolt and head off the threat of civil war.&nbsp;&nbsp;</b></span><br></div><div><br></div><div>The rapidly escalating events mark the most serious challenge yet to the Russian president's rule — and Russia's most serious security crisis since the strongman came to power in late 1999.</div><div><br></div><div>Putin's spokesman insisted the Russian leader was still at work in the Kremlin and had not fled Moscow, as regular forces launched a "counter-terrorist operation" to halt the rebel advance in the Voronezh region, on the Wagner force's route to the capital.</div><div><br></div><div>The governor of the Lipetsk region, whose capital is just 420 kilometers (260 miles) south of Moscow, said Wagner's private military force was "moving across" the territory and urged civilians not to leave their homes.&nbsp;</div><div><br></div><div>Ukrainian leaders, meanwhile, reveled in the outbreak of in-fighting among its Russian foes, with a deputy defense minister describing it as a "window of opportunity" for Kyiv's latest counteroffensive to rid its territory of Russian forces.</div><div><br></div><div>Wagner chief Yevgeny Prigozhin, once a close Putin ally, said his troops had taken control of the military command center and airbase in the southern city of Rostov-on-Don, the nerve center of Russia's offensive in Ukraine, and vowed to topple Moscow's top military leaders.</div><div><br></div><div>"We got to Rostov. Without a single shot we captured the HQ building," he said, in an audio message on social media channels, claiming that local civilians had welcomed the operation.</div><div><br></div><div>"Why does the country support us? Because we went on a march of justice," he said, claiming his men had not killed any soldiers despite having been hit with strikes from army "artillery and after that from helicopters."</div><div><br></div><div>Responding to the challenge in a televised address, Putin accused Prighozin — whose private army provided shock troops for Moscow's offensive in Ukraine — of a "stab in the back" that posed a threat to Russia's very survival.&nbsp; According to AFP reports&nbsp;</div><div><br></div><div>bnbd24/fas</div>