Comment by lopsotronic

2 is almost unimaginably worse.

Nuclear explosives are good. They are very good, as in, "the invention of fire" good. Once the cat is out of the bag on First Use, militaries around the world will put them in operational planning for literally anything that can carry 100kg and needs to strike a hard or spread out target.

That's assuming this conflict doesn't immediately escalate, which is not a given by any stretch.

At the start of WW1 everyone thought that Europeans would hold themselves to proper civilized weapons to use against Proper People. Then someone brought in the weapons reserved for colonized peoples - i.e. "half-people" - and found they work real good on Proper People as well. Uncorking nuclear first use will be like the introduction of the machine gun to the world of war, except every bullet is the most powerful device made by Man.

Breaking the first use taboo - for goddamn Iran of all people - would probably be the worst decision in human history.