Russia has stated they will hit back.

The fact is these weapons are given by the US, targeted based on US intelligence from operators outside Ukraine, and almost certainly fired with a push of the button by US forces or only upon US approval. The US is entering the war as a direct combatant and Russia claims to be growing tired of their salami-slicing tactics (honestly who can say though, the war of words has been at maximum for a while now and Russia seems to be trying to manage the west to prevent escalation which unfortunately allows some degree of escalation and may be taken as weakness by the west and a sign to push things up to the point there is no going back).

Russia has stated they reserve the right to strike the US, any parts of NATO responsible for this (intelligence centers, etc) in retaliation AND that if the US escalates in response to such strikes that they will deploy and use nuclear weapons.

Things are getting very bad, very quickly as the failing west desperately tries to hold onto its hegemony. Russia is fully aware of what their victory means for that hegemony and the west seems so as well. So we're stuck between a rock and a hard place. Russia cannot accept a rump state along current lines armed to the teeth by NATO, the west cannot accept a loss.

Will we all die in nuclear fire? Will saner heads prevail? I know it's not reasonable but I kind of wish for a movie moment here, for trains and trains of DPRK or Chinese soldiers to show up at the Ukraine front, overwhelm the Ukrainians and quickly put an end to the conflict before the west can escalate.