The Wagner Group’s mercenary forces, according to the British military ministry, look to be moving in the direction of Moscow, posing the largest security danger to the Russian state in recent memory.

In an urgent televised address on Saturday, Russian President Vladimir Putin declared the Wagner Group’s “armed mutiny” to be treason and threatened to execute anyone who had used force against the Russian military.

“Over the coming hours, the loyalty of Russia’s security forces, and especially the Russian National Guard, will be key to how this crisis plays out,” the British defence ministry stated in a routine intelligence update.