What is the plan if Putin drops a tactical nuke on Ukraine?

now Putin has been escalating tensions suggesting that he might drop a tactical nuke on Ukraine. Are we going to do if he does that? Biden is so much of a coward that I don’t think he’ll do anything or he’s an actual war monger because he basically encourages war in Ukraine I think to take off the heat for the war in Afghanistan ending in such a major debacle so he doesn’t wanna look like a total freaking moron even though he already does and a coward which he already is and not saying anything but I don’t think he actually has a plan so what happens next after the tactical nuke is dropped

What is the plan if Putin drops a tactical nuke on Ukraine?
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