Russian president Vladimir Putin’s announcement on September 21 of a partial mobilization of up to 300,000 reservists to fight in Ukraine is the clearest evidence yet his regime is in grave danger. Putin is stuck in a quagmire, where the clearest way out is to stop, turn around, and go back out of Ukraine the way he came in. Yet leaders stuck in an unwinnable war often just wade deeper into the muck. Putin is following that well-charted path, and his regime may not survive. Ukraine’s military offensive has turned the course of war and put Russia in an incredibly perilous military position.