Why Trump pulled out of the Iran deal, and what could happen next

President Trump has killed the 2015 Iran nuclear deal, also known as the Joint Comprehensive Plan of Action.

If there was a way to fix the deep flaws of the deal, that probably would have been optimal. Such a revision would have ideally addressed the core flaws that President Obama and the other original negotiators failed to tackle, including the lack of intrusive inspections, Iran's missile program, expiring terms of the deal, and more.

Trump and his three transatlantic European partners (UK, France and Germany) have labored to reach common ground on these issues. But it never seemed likely that the two sides would bridge the gap.

The Europeans were looking to avoid renewed confrontation with the regime in Iran and also cash in on the deal by way of investment there. For his part, Trump wanted to address the fatal flaws of what he saw as a travesty in American diplomacy, but also to isolate Tehran for a long list of malign non-nuclear behaviors — such as supporting terrorist groups, backing the Assad regime in Syria, human rights violations at home, and more.

In other words, the talks were doomed from the start.

With no path toward compromise, Trump followed his instincts. And his instincts were to kill the deal. Once he made his decision, there were no viable half-measures on sanctions. Re-imposing some but not all of the tough financial strictures would muddle the message and make for messy compliance among our allies and adversaries, alike.

The roll-out of U.S. punitive measures figures to be chaotic enough as it is, given the depleted ranks at the State Department, not to mention the complex rules and regulations that the Treasury Department will be required to spell out to central banks and financial institutions around the world.

So, if Trump was going to scrap the deal, it was better for him to return to the sanctions regime we had prior to the deal instead of trying to create an entirely new system that would sow confusion.

It's back to the future for U.S. sanctions now. Our old restrictions, including a mandatory reduction in purchases of Iranian oil, will be re-imposed over the course of the next six months. This will allow for the international community to prepare for the renewed isolation of Iran.

As for what actually happens after that, it is anyone's guess. Iran could stay in the deal with the remaining parties, or it could respond by further destabilizing the Middle East; reports at the time of Trump's announcement suggested that Iran was possibly preparing for strikes against Israel. The Europeans could fall in behind Trump, or they could refuse to comply with U.S. sanctions.

For the United States, the path should be clear. If we are to reinstate financial and diplomatic pressure on the regime in Tehran, that pressure must be overwhelming. It must impose so much economic pain that Iran permanently quits it quest for nuclear weapons while also terminating the malign activities that have terrorized the Middle East since the Islamic revolution in 1979.

The toughest opponents of the Iranian regime would like to see the sanctions precipitate the collapse of the Islamic Republic. The recent unrest on the streets of Iran, inextricably linked to the regime's mismanagement of the economy, suggests that such as a goal is not impossible.

Still others would like to see the pressure bring the Iranians and our international partners back to the negotiating table. In other words, even though Trump has scrapped the 2015 deal, his move on Tuesday could prompt enough panic among the stakeholders that they agree to negotiate a new deal that finally addresses the issues that the JCPOA did not.

The worst outcome would be a squandered opportunity. Trump has done something that even the fiercest critics of the Iran deal never thought possible. Let us hope that he has not done this merely to prove a point about the mistakes of his predecessor. This is an opportunity to correct them.

Jonathan Schanzer, a former terrorism-finance analyst for the US Department of the Treasury, is senior vice president at Foundation for Defense of Democracies. Follow Jonathan on Twitter @JSchanzer.

Follow the Foundation for Defense of Democracies on Twitter @FDD. FDD is a Washington-based nonpartisan research institute focusing on national security and foreign policy.