ROBERT SIEGEL, HOST:

Senator Dan Sullivan sits on the Armed Services Committee. He's an Alaska Republican. Sullivan was an assistant secretary of state during the George W. Bush administration, during which time he worked on sanctions. And he's been a critic of the Iran nuclear deal. Senator, welcome to the program.

DAN SULLIVAN: Good to be here, Robert. Thanks.

SIEGEL: Earlier this year, you said that President Trump should let the Iran deal fail on its own. Are you now going further than that, saying it should be declared a failure and sanctions should be imposed straightaway?

SULLIVAN: Well, actually I didn't say he should let it fail on its own. I said he should vigorously enforce it. And that's still my position. I think that, you know, almost before the ink was dry, Iran was clearly violating the spirit and I think the letter of many elements of the agreement. So to keep U.S. leadership, I think we shouldn't walk away from it. We should vigorously enforce it. Try to get the parties in Iran to correct the violations. And if not, then take action, including the possibility of snapback sanctions like Secretary Kerry and President Obama talked about.

SIEGEL: But the chairman of the Joint Chiefs of Staff, General Joe Dunford, told your committee this week that Iran, in his words now, is not in material breach of the agreement. And he said that he thinks keeping the agreement is in America's national security interests. What's your reply to General Dunford?

SULLIVAN: Well, look. As you can imagine, I have a lot of respect for General Dunford, General Mattis. I'm not sure exactly what he means by material breach, but I believe that Iran is clearly defying the spirit and letter and intent of the nuclear deal. And again, I think the president should take the leadership position of pointing that out to all the parties, including Iran, where they're violating it and say, you have the opportunity to cure the violations. And if you don't, then we're going to take actions pursuant to the agreement, which would include snapback sanctions.

SIEGEL: But just to pursue what might be being in material breach and not being in material breach, you have written about some Iranian actions you say are violations of the deal. But has Iran moved any closer to having a nuclear weapon since this deal to took effect?

SULLIVAN: Well, look. I think the entire - I don't know the answer to that, to be perfectly honest. But I think when you look at the broader issue, there is a clear violation, for example, of the amount of heavy water that they were allowed under the agreement. There's a connection with regards to the ballistic missile testing that they've been undertaking in violation of U.N. Security Council Resolution 2231.

So the agreement can't just be looked at just solely from the objective of, have they move forward more closely with regard to nuclear weapons? It needs to be looked at in terms of the overall spirit and what they committed to do. And Robert, on a number of things, what they committed to do, they've already violated.

SIEGEL: But Secretary of State - former Secretary of State Kerry has written about negotiating this deal. And first he said, you know, what we really can deal with, what really was urgent here was the nuclear program. We have lots of other disagreements. We have many other problems with Iran. But this was the one that there was broad consensus among our other members of the Security Council to address. And so, yeah, it doesn't cover every other issue. It deals with the nuclear program. Isn't that what it's all about?

SULLIVAN: Well, but again, it's not just the violations that I've had problems with with regard to the agreement. It's the overall structure of the agreement. Remember; even if Iran is completely abiding by all elements of this nuclear deal, by the end of the decade, even less if they've complied with it, the agreement almost allows them to legally be on the threshold of being part of the community of nations that have nuclear weapons. I think having another rogue terrorist regime on the verge of having nuclear weapons is not in the interest of the United States. It was one of the big flaws of the deal. And right now they're showing that they're not in compliance with it.

SIEGEL: Senator Sullivan, thank you very much for talking with us today.

SULLIVAN: Thank, you Robert.

SIEGEL: That's Senator Dan Sullivan, Republican of Alaska. Transcript provided by NPR, Copyright NPR.