those other countries may be worse than i realize, but that doesn't mean iran should have nukes. if we could have stopped the other countries, we should have too, if they are bad actors. do you seriously think it's alright for evil countries should have nukes?
Try and look at it this way.
There are a bunch of kids on a playground. Some kids are bigger than others. Some kids are more aggressive than others. And some kids have sticks and some kids have knives and some kids have slingshots and then one day, one of the kids gets a gun.
That kid (USA) with a gun can automatically get cooperation from the other kids without even brandishing the gun. Everybody on the playground knows they have the gun. Everybody knows what happened when they pulled the trigger on Hiroshima and Nagasaki.
Then some other kids get guns (Russia, China) and they feel more secure, they don't feel implicitly coerced by the USA. They feel they can negotiate as equals.
Then the USA starts giving guns to their friends. Then Russia and China start giving guns to their friends.
Then the USA and Russia and China (UN Security Council) realize this is getting a little out of hand and decide to sign a non-proliferation treaty that basically says, "everyone who has a gun can keep it, but no new guns".
North Korea and Iran say, "you're not the boss of me, you guys aren't the king of the world, if I can figure out how to build a gun, you can't stop me".
Nobody "granted permission" to the USA and Russia and China before they got their guns.
The USA doesn't have any right to make rules for SOVEREIGN COUNTRIES.