President Trump's decision to abrogate the Iran nuclear deal was supported less by a threat from Iran than by a misrepresentation of what the Joint Comprehensive Plan of Action (JCPOA) achieves.
The big picture: Many of the reasons Trump laid out for withdrawing from the JCPOA today were inaccurate. The deal does not pave the way for Iran to "reach the brink of a nuclear breakout"; in fact, it extended Iran's nuclear breakout time from about a month to more than a year. It also rolled back Iran's existing program, kept it under strict limitations and included a pledge from Iran that it would never seek a nuclear weapon.
Although Trump said the JCPOA imposed "very weak limits on the regime's nuclear activity," it actually represented the most intrusive inspections regime in the world, as attested to by IAEA Director Yukiya Amano.
Trump depicted Iran as implacably in pursuit of nuclear weapons and likely to dash for a bomb as soon as the deal's "sunset" provisions come due. However, Iran abandoned its nuclear weapons program many years ago, opting against isolation from the international community and the global economy and reducing the risk of preventive attacks by the U.S. or its allies.
What's next: Iran and the rest of the P5+1 may try to salvage what's left of this deal without the U.S., but it won't be easy. Iran will see much less economic benefit and be incentivized to avoid the deal's restrictions, possibly circumscribing inspections, rebuilding its uranium stockpile and shortening its breakout time.
The bottom line: Per the IAEA, the U.S. military and intelligence community and the other parties to the agreement, Iran was in full compliance with its end of the bargain. By abrogating the deal, Trump has isolated the U.S., undermined non-proliferation and increased the risk of another disastrous war in the Middle East.