TEHRAN – Richard Nephew, who served as the lead sanctions expert for the U.S. team negotiating with Iran, is of the opinion that “I think it is likely that Mr. Trump will decline to certify that the JCPOA is in the U.S. national security interest when he needs to next make that judgment (October 15).”

Fellow at the Center on Global Energy Policy at Columbia University, says “My guess, right now, is that it would be politically hard for Republicans to stand apart from the president.  But, it depends a bit on how he chooses to describe his decision and his strategy.”
Following is the text of the interview with Nephew:
Q: Some sources in West has announced that Donald Trump will declare non-commitment of Iran to JCPOA probably. What’s your opinion?

A: I think it is likely that Mr. Trump will decline to certify that the JCPOA is in the U.S. national security interest when he needs to next make that judgment (October 15).

Many members of Congress are concerned about Iran, but they are also concerned about the proliferation of nuclear weapons and fear that any damage to the JCPOA could increase the chances of such proliferation.

Q: If Trump violates JCPOA, what will be the next step against Iran?

A: This is where the issue gets more interesting.  Refusing to certify the agreement is in the U.S. national security interest is not, in and of itself, a violation of the JCPOA.

Reimposing sanctions that are supposed to be suspended or terminated would be a violation of the JCPOA.
Similarly, imposing these same sanctions but claiming that they are in support of addressing Iranian support for terrorism, violations of human rights, missile tests, etc would also be a violation.
Refusing to certify the agreement only requires Congress to consider whether or not to reimpose sanctions.  So, that is both all that is required and all that is certain to take place.
Trump may decide to approach Iran for negotiations on an alternative for the JCPOA or an additional agreement on top of it, but this remains unclear.

Q: The U.S. Congress has to vote for turning sanctions against Iran back if trump decides to violate JCPOA. Will U.S. Congress take such decision in companionship with him?

 A: I do not know.  Many members of Congress are concerned about Iran, but they are also concerned about the proliferation of nuclear weapons and fear that any damage to the JCPOA could increase the chances of such proliferation.

Trump may decide to approach Iran for negotiations on an alternative for the JCPOA or an additional agreement on top of it, but this remains unclear.

This includes both Democrats and Republicans, who could normally be counted upon to take a more hardline stance.
My guess, right now, is that it would be politically hard for Republicans to stand apart from the president.  But, it depends a bit on how he chooses to describe his decision and his strategy.

Q: Some persons like Richard Goldberg believe that EU will companion Trump, if U.S. president decides to violate JCPOA. What’s your idea?

A: Having been responsible for implementing these sanctions, I believe that it is easier to say that other countries will cooperate with the United States than to make it happen.  It was a lot of hard work that made U.S. sanctions carry weight in Europe and elsewhere.
 I think that Mr. Goldberg underestimates this hard work and the degree to which context matters.  In the past, Iran was in active violation of its NPT Safeguards Agreement and there were questions as to its nuclear intent.  Today, Iran is -- according to the IAEA -- acting in conformity with its NPT Safeguards Agreement and the JCPOA.  This context will make it much more difficult to persuade other countries to follow the U.S. lead.