What doesn't make sense is that you are going into negotiations with another nuke capable country and you violate another treaty with another country at the same time. Weather you are for or against the US pulling out of the Iran deal, does it not seem stupid to make a decision like this when you will be looking to do something very similar with NK.
Here is the other stupid part. So the US pulls out of the Iran deal but without the other countries doing the same. Next, Trump administration says the will impose the most restrictive sanctions on Iran every. The dumb part is that we do not do any business with Iran. The US can sanction the crap out of Iran and it means absolutely nothing if the rest of the world is not also doing the same. Since Trump did not use his great negotiations skills to convince the EU, China and the rest to follow his lead, basically we just swinging in the wind. The other nations will continue to deal with Iran as usual and our sanctions will be just some stupid political talking point for Trump with no meat.
So basically the US just pulled out of another deal and the rest of the world just moves on without us. Pretty soon the US say in international affairs will be nothing. Instead of leading we will be this nice isolated country with this large military where the rest of the world ignores us.
My opinion about is leaving the Iran deal is more on timing and not getting support from the rest of the world then the US actually pulling out. It just seems that the rest of the world will ignore this administration and look to another big power like China to get things done instead of the US. Our leadership abroad will erode as it has been. Long standing allies will not trust this administration word on anything and other countries that look at us as treats will be less likely to go into any deal believe that at a whim we will pull out or want to change the terms. This is how Trump ran his businesses but if anyone believe that is how you run a nation, you will see there are ver big consequences to that approach.