In past generations, it has been the brutal Russian winter which has
stopped invaders.
   This person points out that this time, the systemic corruption,
along with Ukrainian attacks, may be just enough to freeze and starve
both the Russian army in their trenches, and the civilians in their
towns and cities. Everywhere, food and fuel of all types is in short
supply, with both military and civilian logistics pretty much broken
down.
https://www.youtube.com/watch?v=pE1N5V0sz-0&t=295s

Maranatha, Lewis Brackett