The US did disarm somewhat after the Cold War, but kept a lot in place for pork-barrel reasons and then the absolutely huge waste of money that was the War On Terror.

People believed the "end of history" narratives about Russia, and even that it would become like the rest of the ex-communist states, a normal part of liberal Europe. That should have changed after 2014, but by then the grip of the financial crisis was preventing any increases in state spending.