Sorry pussy, we don't let nuclear blackmail permit totalitarian regimes to gobble up countries. Same logic would require China taking Taiwan, and then Japan, Korea and Australia, whom China has all threatened at one time or another. Australia, like the USA, was identified by them as a nice place to "colonize."
Regardless, we already crossed all of Putin's red lines. He kept repainting them with zero effect or push back despite promises of "unprecedented consequences" "never seen before in world history."
On our way then to WWIII.