Google which countries have nuclear weapons. Hint: It’s not just the US, it’s also its allies and frenemies who’ve not been invaded. It’s only nutball countries like Iran that get invaded when on the cusp of acquiring it and for good reason.
There is strong evidence that Iran was not as close to a nuclear weapon as you say.
We will find out the truth eventually, like we found out that the WMDs in Iraq claim was a complete lie.