He single-handedly, with one move, completely destroyed America's ability to be taken at it's word in any form of negotiation or deal with any country in the world. By openly bragging about using the nuclear talks as a means of lulling Iran into a false sense of security so that Israel could attack them, he displayed to the entire world that America cannot be trusted. That is not what you want when America's soft power is fading away around the globe and more and more countries are flocking to China. If it were anyone else, America would still have a chance at being respected.