Its important to remember that the US leaving the deal isn't just Trump acting on his own accord. This is a joint effort by the U.S., Israel and Saudi Arabia.
Already the Israeli Air Force has attacked Iranian forces in Syria. They are doing this simply to goad Iran into attacking Israel thus providing the West with the reason to invade Iran. You can expect Saudi to bomb the heck out of Yemen in the next 24 hours. All done with the hope that Iran will react.
Another point to be noted is that the U.K., France, Germany & Russia have not left the deal and apparently have no intention of. So that just confirms that this a plan hatched by the U.S., Israel and Saudi.
Perhaps this is the moment that children in History class will look back upon a century from now and learn that this was the moment that set off WWIII and they will react with a collective facepalm about how stupid leaving the deal really turned out to be for that trio of countries to say nothing of the millions of lives that were lost in the subsequent war.
^ . This is a strategic chess game. The Pro Zionists in the US Govt (which there are many, including Trump, which should be obvious to everyone by now), Israel, and Saudi are attempting to push Iran into making a provocative move toward Israel, US, or Saudi so they can use it as a justification to attack Iran militarily. They have been trying different things for a while now, none have worked so far. They need a solid justification in order to get the European Governments to assist them or at least remain silent so they can pretend that the 'whole world' is agreed on this military move. They also need Russia and China to sit on the sidelines, since they know they probably will not assist them. They are supposing that with Saudi, Israel, US, and European governments participating in the attack and Russia and China sitting on the sidelines, they have a good chance to hand Iran a sound military defeat.
Iran has made a very intelligent move, in this case. They have not withdrawn from the deal, but are saying they will work with Russia, China, and the European Govts in order to keep the deal in place without the US. I'm not sure if this will work, but it is a good move anyway, InShahAllah it will work. If Iran withdraws completely and restarts uranium enrichment in full, then most likely this will lead to a military confrontation, as Trump and his buddies will then come up with some fabricated evidence that Iran has a nuclear weapon and will use it as a basis for an attack, exactly what George Bush did in 2003. If he tries this, I think there will be a huge pushback by the American people, the vast majority of whom will be against this attack. But they figure they have just enough political 'juice' to push it thru and then get their payout. If they do the attack, it will almost surely be before Nov elections in the US, because after the elections Republicans are going to lose both the House and Senate, and Trump will be impeached or resign. Trump knows he has very little time left as president, which is why he is moving fast on his agenda.
In reality, Trump came into office with only two agenda items, all the rest are simply a smokescreen
1) Give big tax cuts to please his rich donors, which he has done
2) Attack Iran to please his Zionist buddies. This is what he is trying to do with this move.