A deep strike into Russia could be counter-productive by giving the Russian People cause to support the illegal War kicked off by Putin and his cronies.
They did not care much for the Russian affair in Afghanistan....so why risk alienating any popular opinion for little military gain?
Mothers are seeing their Sons head off to Ukraine and coming home in Caskets....or not coming home at all.
Learn a lesson from other Nations that have conducted unpopular Wars....say.....like maybe the Falklands were the Argies thought they could do something similar to what is going on in the Ukraine.
How did that turnout for that Regime?