If the Russians do not want to be attacked within Russia then they should stop attacking Ukraine. You reap what you sow. (And no, this will not start WWIII.)
You neo-libs really aren't very bright.
Nobody can predict how the Russians would respond if they are attacked in Russia with US & Nato supplied weapons. The Russian government & military leadership are fully invested in the Ukraine war, but perhaps the majority of the Russian population are not. An attack inside Russian with US & Nato supplied Russia would solidify support for Putin from the Russian populace, as 9/11 unified Americans for a while. I don’t think Russia would nuke the US, or any Nato country, but I wouldn’t put it past them to use a tactical nuke in the Ukraine to up the ante.
If NATO weapons rain down upon Russia, irrespective of their site of launch, aren't NATO and Russia officially at war at that point? I say "officially" because NATO and Russia are at war now but it's a proxy war, at present; Ukraine is NATO's proxy. If a NATO vs Russia conflict isn't WWIII, what would constitute WWIII? Is the use of nuclear weapons obligatory before it can be called a World War?
NATO includes the US. If US weapons are shot at Russia, Putin will return the favor. There is zero doubt about that.
Further US meddling in Ukraine will result in them ceasing to be a Nation, as it should.
Ukraine had many chances to negotiate a settlement, most notably when one was achieved and Boris Johnson flew in and torpedoed it….proving the West can NOT be trusted, ever.
Russians had a reasonable peace offer at the start of this war, but neoCON scum like you would not allow peace. The neoCONs demanded the death of 100s of thousands of white Christians so they could make money for the MIC. Just watch. The neoCON scum will now advocate importing millions of muslims into Ukraine to “rebuild” it - all for the MIC to make a buck and to eliminate Christianity just like their non-Christian faggot hero is banning Christian churches in Ukraine. These neoCON scum want one-world government and destruction of Christianity and Western Civlization is part of their plan to make it happen. These are seriously disturbed individuals who have made a deal with the devil.
The Russians were pushed into it. There was a deal in place but globohomo dispatched Boris Johnson (who should be executed) to kill the deal.