There's this picture I keep thinking about.

A picture of the way things used to be when it came to American foreign policy.

It was taken back in 2015.

The Iran nuclear deal had just been agreed to in Vienna.

In this picture, then Secretary of State John Kerry is on a government plane with his lead negotiator, Ambassador Wendy Sherman.

They're on their way home. They look relieved.

They've got glasses of wine in their hands.

We opened the bottle. We handed out plastic cups, took a sip.

That was our celebration.

And immediately everyone on that

airplane just passed out in exhaustion. I've been thinking about that photo of Ambassador Sherman

because in it, she's got this satisfied smile of someone who's just done something really

difficult, almost impossible. We were humbled by the historic nature of this agreement.

Nobody wants Iran to have a nuclear weapon.

So I think we all understood the gravity of what we had done, but also what was before us.

You've said that during negotiations, the Iranians asked.

They said, what do we do if another administration comes in and just blows this thing up?

Because as you said, it wasn't a treaty.

It was an executive action.

And so any executive could change that action.

So whenever the Iranians asked me that question, it was often, I would say back to them,

how do we know that your government won't change?

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