I actually disagree, Iran has been complying with the deal:
https://www.vox.com/world/2018/5/8/17328858/iran-nuclear-deal-trump-announcement-chart
I also do not think Trump has a plan B - he simply did this because his Zionist cabinet members and Netanyahu wanted him too.
That's right, Netanyahu played a crucial role for Trump to abandon the agreement. It only remains to wait for the consequences of the decision.