What do we do?
The emotional response:
Tell Putin it's time for him to retreat.
Tell him the US will drive his troops from Ukraine but will not follow them into Russia.
Tell him if he launches a nuclear first strike we will destroy Russia several times over.
Tell him if he's the one that brings about Armageddon, that will be his place in history... if there's anyone left to record it.
It's either that or simply keep supplying Ukraine and hope for them to hold onto what's left.