If NATO was attacking Russia instead of offering Ukraine some fairly minimal support, You'd see the 82'nd Airborne and 101st Airmobile dropping into Sevastopol while the British 7th Armored Division, the US 1st Armored and 1st Cavalry divisions supported by the US 1st, 3rd, 4th and 7th Mechanized Infantry Divisions accompanied by about thirty French armored and armored infantry regiments crossing from Ukraine and the Polish 1st Legions Infantry division, the Polish 11th Armored Cavalry Division, the Polish 12th Mechanized Division, the Polish 16th Mechanized Division and the Polish 18th Mechanized Division supported by the US 10th Mountain Division coming out of Poland and various odds and sods from Norway, Sweden, Finland, Denmark and the Baltics coming out of Sweden and Finland plus a bunch of odds and sods coming out of the Balkans. You'd be fighting a FOUR FRONT WAR against opponents with superior numbers, superior equipment and a coherent strategy. Not to mention the US Pacific Fleet attacking Vladivostok and landing US Marines there as occupiers.
Russia would fold like a wet Kleenex against that kind of force.