why is nato,and america,and israel concerned about iran,and n.korea having nuclear weapons? when they have them,?

The reason for the Iran deal was so Iran wouldn't get nuclear weapons. Since Trump pulled out of the deal I suppose Iran said why should we follow the deal if the USA doesn't want to follow the deal. The big mistake was the USA pulling out of the deal.

sam,you just hit a home run,that's where the problem lies

Why do I worry more about criminals having weapons -- and not so much the police -- ,or  drug pushers pushing drugs -- and not so much doctors ?

It's about rational value judgements 

If Iran really wanted a nuclear non, they would have  bought one from n Korea.

Israel is the warmonger and is the one who never signed the nuclear nonproliferation treaty.

You cannot dictate to those with nuclear weapons.  Nobody has ever used them except for the USA in WWII.  They are a deterrent from getting attacked, which means loss of control of the region.

China has them, Pakistan has them, Russia has them.

It's called Nuclear proliferation. They want to control who gets nukes because they re so f'ckin nut s'hole leaders in North Korea and Iran..Iran doesn't like the government of Iran, and North Korea doesn't like its government.

China, Russia, the UK, France, India, Pakistan and most other nations are concerned. 

Why aren't you? For patently obvious reasons.