US President Joe Biden has been briefed and his administration is closely monitoring fast-moving developments in Russia as Vladimir Putin vowed “decisive actions” to suppress mercenary leader Yevgeny Prigozhin and his armed rebellion. “We are monitoring the situation and will be consulting with allies and partners on these developments,” according to a statement on Friday night from National Security Council spokesman Adam Hodge. Prigozhin – once a longtime ally of Putin – is accused of treason for mounting what Russian officials have called an armed rebellion with his Wagner paramilitary group, fuelled by allegations that Russia failed to adequately support his forces in Ukraine. He also has accused Russia’s military leadership of striking against his forces. US Secretary of State Antony Blinken said on Saturday that he has spoken with G7 foreign ministers and European Union officials “to discuss the ongoing situation in Russia”. “The United States will stay in close coordination with Allies and partners as the situation continues to develop,” he added. US Secretary of Defense Lloyd Austin Defense also is monitoring the crisis, according to Pentagon spokesman Patrick Ryder. Canadian Prime Minister Justin Trudeau also has been briefed on the situation. Canada’s Incident Response Group will meet on Saturday to discuss developments. “We’re in contact with our allies and will continue to monitor the situation closely,” he announced on Saturday. Russian prosecutors have launched a criminal investigation. In a televised address on Friday, Putin called Prigozhin’s maneuvers “a stab in the back of our country and our people”. The Wagner group was designated a transnational criminal organization by the US in January. National Security Council spokesman John Kirby said the group had an estimated 50,000 personnel inside Ukraine made up of 10,000 contractors and 40,000 people enlisted from Russian prisons. Wagner’s armed convoys have moved into Rostov-on-Don, the largest city in southern Russia and roughly 100km from the eastern Ukraine border. Rostov, with a population of roughly one million people, also houses Russia’s southern military district command and the 58th Combined Arms Army, currently engaged in major counteroffensive efforts against Ukraine. The governor of Russia’s Lipetsk province announced on Saturday that the group has now entered that region. Prigozhin also was among 13 Russians indicted by a federal grand jury for interfering in the US elections in 2016, allegedly using his Russia-based Internet Research Agency to wage “information warfare” with false social media accounts promoting bogus statements and messages that supported Donald Trump. He has denied wrongdoing but remains wanted by the FBI. Read More Russia-Ukraine war live: Kremlin denies Putin has fled Moscow as plane mysteriously disappears from radar Who is Yevgeny Prigozhin? The Wagner Group mercenary chief urging a ‘civil war’ against Putin Rishi Sunak ‘in touch with allies’ about Wagner group rebellion in Russia