Once a low-profile businessman who benefited from having President Vladimir Putin as a powerful patron, Yevgeny Prigozhin moved into the global spotlight with Russias war in Ukraine.

As the leader of a mercenary force who depicts himself as fighting many of the Russian militarys toughest battles in Ukraine, the 62-year-old Prigozhin has now moved into his most dangerous role yet: preaching open rebellion against the leadership of the countrys military.

Prigozhin, owner of the Kremlin-allied Wagner Group, has escalated what have been months of scathing criticism of Russias conduct of the war by calling Friday for an armed uprising to oust the defense minister. Russian security services reacted immediately, opening a criminal investigation and urging Prigozhins arrest.

In a sign of how seriously the Kremlin took Prigozhins threat, riot police and the National Guard scrambled to tighten security at key facilities in Moscow, including government agencies and transport infrastructure, Tass reported. Prigozhin, a onetime felon, hot-dog vendor and longtime associate of Putin, urged Russians to join his march to justice.