That would be a violation of the rules that both sides have agreed upon in order to conduct a friendly war.If NATO doesn't respond, then there is no NATO. And I'm not talking just supplying some weapons. I'm talking destroying that 40 mile long Russian military caravan with airpower and installing a no fly zone over Ukraine. Ukraine deserves better from the asshole countries who claim to love freedom.
For now at least, back off to some possibility of the Ukraine destroying it. There's just no way Putin would have placed his army in such a vulnerable situation in which America could win the war quickly.
It would be virtually the same as America lining up it's heavy artillery in Iraq that would have made them sitting ducks for any large and powerful foe! Or, placing an aircraft carrier in a vulnerable position?