So you are proposing that the air force can just start pummeling the air defences around Moscov? Because that would be a viable counter step if not for MAD.

A viable counter step would be to deny Russia air superiority in Ukraine and to attack any troops crossing the border from Belarus, for example. Not to go and attack the capital of Russia.

Yes, I don't understand why Biden is being shy about this.

You mean besides the reason that he is borderline senile and has been a completely ineffective president in every other regard besides Ukraine?

I don’t think ‘the air force’, whichever that may be, has enough assets nearby to do such a thing, nor that it would be particularly productive even if you ignored MAD.

The goal here is to prevent one invasion, not start another one.

But there ought to be enough fighters in Europe to swat anything flying in Ukraine out of the sky.

The world would have ended by now had people followed that advice 50 years ago