It worked once, against Kim Jung-Un! When a blustering Trump started threatening fire and fury, the Korean leader who had thus far proven to be as stubborn as Trump; having proven that he had developed the capability to launch an intercontinental nuclear ballistic missile at the USA decided enough! He has now charmed his way into the hearts of both Moon Jae-In (South Korean leader) and Xi Jinping (Chinese leader). He has even shown a willingness to give up his nuclear ambitions but only as a mutual agreement to nuclear disarmament of the peninsula. Madness yes, but some might even call it genius. Whether or not he deserves a Nobel peace prize is remains highly debatable. But let's take things in context for a moment.
When in the mid-1930's Hitler started usurping power, there were many that cheered him on. Why? Because his stated motives at that time seemed noble. His main audience, was a pissed-off and starving German nation from the terms and conditions of the Treaty of Versailles that ended WWI (1919). When he started making threatening sounds in Poland, Belgium there were even British advisers that told Churchill to remain neutral because Hitler was too strong. That was when the world learnt a valuable lesson. Just because you are strong, just because you have the ability, just because you won the war; if you push too hard and punishment is too great, a resentment develops and continues to fester and develop until eventually the cauldron boils over.
The Iran treaty signed under Obama had one major goal, to stop Iran developing nuclear weapons. It was working, and if the Iranian regime abused this new found wealth to provide support for known terrorist groups, then certainly it is a problem to be looked at. But let's not kid ourselves. The Saudi's weren't much better, Israel, Russia, USA and the UK all supported their flavour of choice thereby turning Syria into the first killing grounds of the 21st Century.
Unilaterally tearing up the Iran deal has completely changed the game in the Middle-East. There is still of course the chance that this is simply the opening gambit, to force Iran to behave. The Europeans, if immigration, the Euro and Brexit aren't problems enough; are now facing the prospect of entering into a war they desperately did not want. Not a bullets and bombs war. An economic war against the US. Unless they follow suit and support these new sanctions imposed by Trump, companies that continue doing business with Iran face the anger of the Americans against them. By contrast, supporting the US risks all out terrorist retaliation against Europe. O course, they would prefer to target the US but they are just too far away. Frankly the moral imperative would be on their side.
The jokers in this pack are China and Russia. As cosignatories and fellow members of the UN security council, what will they do? If they choose to ignore the US then the sanctions won't work. Even if Europe joined the US, we would end up looking as stupid as the Americans. The UN would be weakened even more than it is, NATO would be intact but ...
The only people that gain from this are the Russians, because of the strain this is putting on NATO! Trump isn't simply in collusion with the Russians. He really is Putin's idiot; even if the morons that encouraged him like Sebastian Gorka and John Bolton think they are making America great again.