A few more thoughts on why Trump’s decision on the Iran deal is bad.
US can no longer be trusted
It is important to note that the US is not withdrawing from the Iran deal. It is reneging on it. Some agreements have provisions for withdrawal, and you give notice etc. What has happened here is Trump has said he will ignore the agreement and impose sanctions despite the US having agreed not to.
It actually puts the US in violation of an agreement that was given legal force by the UN Security Council, while NZ chaired it.
Iran has kept up its end of the deal. That is not just my view, but the view of the US Defence Secretary, US Dept of State, NSA, CIA and all the European countries that were parties to the agreement. Iran is far from a model country, but there is no evidence that they have not wound down their nuclear program as agreed.
So what this means is that an agreement with the US Government now means little. At best it is something they may honour for a few years. Trump doesn’t care of course. His only concern is how his decisions impact him. But it will have a profound impact on the ability of the US in future to be able to get agreements.
It strengthens the radicals in Iran
This deal was made by the moderates in Iran and basically opposed by the hardliners. They said you can’t trust the Great Satan and Trump has proven them right. This weakens the moderates and may lead to the hardliners accumulating more power.
This matters, as the difference between a moderate and hardliner in Iran is huge. Far far more difference that between say Trump and Clinton.
It helps Russia and China
The US sanctions stop US companies trading with Iran but in reality few were anyway. The companies affected will tend to be European as if they continue to trade with Iran they will be blacklisted in the US. So only small European countries will continue to trade. But there is no return to a global sanctions on Iran so this will open up huge opportunities for Russian and Chinese companies.
It makes Iran look like the good guy
Iran is not the good guy. They still do many bad things such as support Hamas. They are a theocracy. The Iranian people are wonderful but the Government is not.
However as they have kept to their end of the deal, the US looks like the bad guy and Iran like the good guy. In fact it pushes Europe and Iran closer together as they are looking likely to stay with the deal, despite the US pulling out.