Robert Einhorn is a senior fellow with the Arms Control and Non-Proliferation Initiative and the Center for 21st Century Security and Intelligence at the Brookings Institution. Before coming to Brookings in May 2013, he served as the State Department special adviser for nonproliferation and arms control, playing a leading role in the formulation and execution of U.S. policy toward Iran’s nuclear program with respect to sanctions and negotiations between Iran and the P5+1 countries (the U.S., Russia, China, Germany, France, Britain).

Six months of talks between Iran and the P5+1 countries designed to limit Iran’s ability to develop nuclear weapons were extended last month until Nov. 24. The following is an edited transcript.

Q: I understand significant progress has been made in the talks.

A: There has been progress on some of the major issues. One of the big problems was the reactor at Arak, which the U.S. believes was intended to produce plutonium for a nuclear weapons program. There has apparently been an agreement to redesign the reactor to greatly reduce the amount of plutonium it generates to a level sufficiently small enough that it would not be of concern to a nuclear weapons program.

Another area of progress has to do with the Fordow enrichment facility. This is an underground facility on a piece of land previously used for military purposes, and it was suspected of being a covert component of a nuclear weapons program. But it was discovered by the U.S., Israeli and other intelligence agencies, and since then has operated as a rather small enrichment facility. Ideally, this Fordow facility would be shut down, but apparently there has been an agreement to alter its purpose and to suspend all enrichment there.

It has been argued that Iran really doesn’t want an agreement and is just using the talks to stall while it continues its efforts to build a nuclear weapon. Do you believe that?

Iran genuinely wants an agreement that will lift the sanctions against it. That’s the principle reason why it has engaged in the negotiations. But Iran wants to reach an agreement that involves the least constraints on its nuclear program. The U.S. goal is to have an agreement that puts the maximum constraints on Iran’s nuclear program and its future nuclear options.

Israel wants to see the total elimination of Iran’s ability to develop a nuclear weapon.

Iran won’t agree to zero enrichment. The question is whether it is prepared to have significant constraints on its program to give confidence to the international community that it doesn’t have a rapid breakout capability — that is to leave the agreement and produce a bomb in a short period of time.

Some sanctions against Iran were eased at the start of the interim deal to begin talks. What has happened since?

There was a fear voiced by Israeli Prime Minister [Benjamin] Netanyahu that the interim deal would generate great enthusiasm among the business community throughout the world and that business operations would begin resuming in Iran. But companies have been cautious and are waiting for a complete agreement. So the Iranians have come to the conclusion that the only way to get sanctions removed is for there to be a comprehensive deal.

How badly have the sanctions hurt the Iranian economy?

According to the recent testimony of David Cohen [undersecretary of the Treasury for terrorism and financial intelligence], Iran’s economy is 25 percent smaller than it would have been.

There are reports that Iran wants to rearm Hamas. How might that affect these talks?

Obviously, efforts by Iran to support Hamas in its unacceptable aggression against Israel would not provide confidence about Iran’s overall motivation. Iran’s behavior in the region will affect the receptivity of the U.S. and the world to any nuclear agreement.

Do you believe this four-month extension of the talks will produce an agreement?

I don’t know. Right now the gaps are pretty wide. It’s largely up to Iran.