ROBERT SIEGEL, HOST:
President Trump today threatened to terminate U.S. participation in the Iran nuclear deal unless Congress and the other signatories to the pact make it tougher on Iran. Technically the president is refusing to certify the deal, which he's required to do every 90 days, but he's not walking away from it.
Vali Nasr is the Iranian-born dean of the Paul H. Nitze School of Advanced International Studies at Johns Hopkins University. He's written extensively on Iran and more broadly on politics in Muslim nations. Welcome to the program...
VALI NASR: Thank you.
SIEGEL: ...Once again. You've written an op-ed with the title "Trump Is About To Make The Defining Mistake Of His Foreign Policy." I assume you would say today he made that mistake. Why do you say that?
NASR: Well, because by undermining a nuclear deal that the United States led to negotiate involved a number of other - of our allies, Russia and China, and has been successful to date, by torpedoing it or arguing that it has to be renegotiated, he has seriously undermined U.S. credibility. It's going to make it very difficult to have any other deal of this sort with Iran or any other nuclear actor. But also, this now puts Iran - United States on a confrontational path with Iran. And given the instability in the region, given the situation in Syria, in Iraq, in Afghanistan, it's likely to get the United States more engaged in conflicts in the Middle East and destabilize the region. And I think that's going to end up being his legacy in the region.
SIEGEL: He, though, would dispute that it's a successful deal. First, just as a narrow nuclear deal, he would say, no, the Iranians have been violating the terms of the limits on heavy water. They've intimidated inspectors. Does he have any case?
NASR: Well, he's alone in making that allegation. European leaders have all said that Iran is in compliance with what it agreed to. And also, the signatories of the deal at the outset left the charge of verifying the deal to the International Atomic Energy Association (ph) of the United Nations, which has technicians. And they have gone to Iran. They have inspected it. Iran is under the most intrusive inspection system. And to date they have said that Iran has abided by the terms of the deal. So President Trump is making his own judgment based on his own facts.
SIEGEL: He makes a broader critique, which is not only is it a bad nuclear deal, but it's only a nuclear deal. And in spite of this deal, Iran's missile program goes on and Iran's support for groups the U.S. considers bad actors in the region - the Assad regime, Hezbollah - continues. What do you make of that argument?
NASR: Well, the deal was not supposed to - about everything between Iran and the war. The deal was on the nuclear issue. That was the threat that President Obama tried to address. And if there had been a deal about missiles or about Iran's support for Hezbollah and others, I'm sure that Iranians would have had other issues on the table and they would have got from the United States and the international community other things. I think this is a case of President Trump wanting to put the nuclear deal in his back pocket and then sort of negotiate other things through it.
SIEGEL: Did the nuclear deal, though, liberate Iran to be a more active player, say, in Syria than it was before without concern that the U.S. might attack them at some point?
NASR: No, I don't think so. I think that Iran's expansion - expansion of Iran's role in the region is a function of the collapse of order in Syria, in Iraq, in Yemen, in other places. The other side of it is that, in fact, Iran and the United States collaborated very closely in defeating ISIS in Iraq, which would not have probably been possible had the environment of cooperation that the nuclear deal created hadn't been there.
SIEGEL: Just very briefly, Iran's President Rouhani called Trump's remarks full of insults and fake accusations. He said, Iran will never bow to any foreign pressure. Privately, do you think he's all that unhappy? Or might he be pleased that Trump stopped short of actually breaking with the agreement?
NASR: Well, I think he's happy that the agreement wasn't broken because politically it will undermine him seriously. But I think many in Iran have decided that this deal is about to collapse because Trump has started a process that is going to eventually unravel the deal.
SIEGEL: Vali Nasr, dean of the Johns Hopkins School of Advanced International Studies, thanks.
NASR: Thank you. Transcript provided by NPR, Copyright NPR.