The following is a transcript of an interview with Former Secretary of State John Kerry that aired Sunday, January 12, 2020, on "Face the Nation."

MARGARET BRENNAN: We go now to Dubuque, Iowa and the presidential campaign trail where former Secretary of State John Kerry is on a campaign bus trip with former Vice President Joe Biden and you can hear that bus generator going in the background. Good morning to you, Mr. Secretary.

FORMER SECRETARY OF STATE JOHN KERRY: Sorry about that. Good morning, MARGARET. Good to be with you.

MARGARET BRENNAN: I want to pick up kind of where we just left off with the two senators. You know, you've been touting Joe Biden's foreign policy experience as a reason voters should consider voting for him. Bernie Sanders, his opponent, has- has taken that on as a reason essentially not to specifically focusing in on Biden's vote to help authorize the war in Iraq. He called it appalling that after 18 years, Joe Biden still refuses to admit he was dead wrong in the Iraq war, the worst foreign policy blunder in modern American history. Given what you know about the region and how Iran was essentially empowered by that, why- why doesn't he just call it a mistake?

KERRY: Well, I think I in fact, MARGARET, I think that Bernie, regrettably, is distorting Joe's record in the following sense. I mean, he doesn't have what Joe Biden has, which is eight years of sitting on the National Security Council and demonstrating his judgment, whether it was on his leadership, dealing with the migration that was flowing across our border and helping to resolve that with the presidents of those countries or his work pulling troops out of Iraq and negotiating that and working as perhaps the lead point man on that effort. I think that- that I know very well what Joe's position was, because I answered those questions back in 2002, 2000- 2003 and four. And it was very clear that what we were doing was listening to a president who made a pledge that he was going to do diplomacy, that he was going to exhaust diplomacy, build a coalition. And ultimately we learned, as Joe did and I did, that the intelligence was distorted. So Joe spoke out and criticized. Joe was against what they were doing. The vote was not a vote specifically to go to war. It was a vote for the president to have leverage with respect to getting Saddam Hussein back to the negotiating table, back to the inspections, excuse me. And I think we were let down and Joe has said many times that it was a mistake. Obviously, you trust the words of the administration who didn't follow through on what they said they were going to do. And I invite you to go back, read my speech on the floor and others--

MARGARET BRENNAN: Right.

KERRY: --where I said this is not a vote specifically to let the president go to war. So I think Bernie is trying to drive a wedge in there. I understand that, but I think the vice president has unparalleled demonstrated accomplishment and success in foreign policy as chairman of the Foreign Relations Committee and as vice president. And he, in my judgment, is the one person running for president--

MARGARET BRENNAN: Yeah.

KERRY: --who the moment he takes office, has the ability to be able to address a lot of questions, including the credibility of the United States.

MARGARET BRENNAN: Well--

KERRY: Joe has told the truth. People know that. And I think they will trust in his capacity to lead the country at a very, very delicate time--

MARGARET BRENNAN: Well--

KERRY: --when foreign policy experience--

MARGARET BRENNAN: It is--

KERRY: --is, in fact, a premium.

MARGARET BRENNAN: It is. And Iran, an issue you know well, is front and center right now. But virtually every single Democrat running for office right now is claiming the same or virtually the same Iran policy, which is to try to revive the deal that you negotiated. There's- some would say a shell of it left now. Shouldn't voters expect more out of a Iran strategy from someone trying to be commander in chief?

KERRY: Well, Joe Biden is, in fact, providing more, which is to recognize that- that it's not enough just to go back to where we were because obviously circumstances have changed and things have evolved in the last three and a half years. And- and what- what Vice President Biden knows we have to do is make sure now that all the things that we were going to do in the follow on agreement, which was always contemplated. MARGARET, you were there. You're an expert at this. You know exactly what the truth is about it. We were trying to take the nuclear weapon off the table first and then negotiate Yemen, Hezbollah, threats against Israel, the regional question of trafficking of arms. And- and so Vice President Biden understands that now has to also be front and center --

MARGARET BRENNAN: Yeah.

KERRY: --as you- as you revive the agreement. But the truth is, France, Germany,--

MARGARET BRENNAN: Right.

KERRY: --Britain, China, Russia are all still trying to keep the agreement in place because they recognize it's the strongest, most transparent, most accountable nuclear agreement on the planet, --

MARGARET BRENNAN: Well --

KERRY: -- and it did take a nuclear weapon off the table until President Trump decided unilaterally to ignore all of our allies and move to get out of the agreement.

MARGARET BRENNAN: Well, the president--

KERRY: And everything--

MARGARET BRENNAN: The president's going on the--

KERRY: --that's happened in the last days--

MARGARET BRENNAN: --going on the attack on that deal this morning, specifically mentioning you. Perhaps not a surprise. But, you know, I- I know the deal you negotiated lifted sanctions, gave some relief in exchange for capping the nuclear program. There was also a parallel negotiation that released some cash as part of a settlement of a different, separate dispute. The president this week put blame on the administration, your- the administration you served on with essentially helping to provide money to the IRGC. I want to play a sound bite of what you said in 2016 to CNBC when you were asked about how Iran would spend the money.

(BEGIN CLIP)

KERRY: I think that some of it will end up in the hands of the IRGC or of other entities, some of which are labeled terrorist. You know, to some degree I'm- I'm not going to sit here and tell you that every component of that can be prevented. But I can tell you this, right now, we are not seeing the early delivery of funds going to that kind of endeavor at this point in time. I'm sure at some point some of it will.

(END CLIP)

MARGARET BRENNAN: I remember talking to you at the time. Money is fungible.

KERRY: Sure.

MARGARET BRENNAN: Why, though, did you think--

KERRY: Absolutely. Money is fungible.

MARGARET BRENNAN: --that that was a risk worth taking if you knew the possibility of what would happen with that money?

KERRY: Well, what I was really saying, I think, first of all, MARGARET, you are an expert at this. You were there. You know that the president's tweet is a lie. And the president tweeted this morning, because I am coming on the show and he knew you'd ask me the question or he'd push you in a place where you did ask the question. You and the media, I think, need to call a lie a lie. You know--

MARGARET BRENNAN: Mr. Secretary, I asked you that question in 2015 too.

KERRY: --they didn't get 150 billion dollars. No- no- no. But let me just finish. You know- yes. And I'll- I'll answer that. I was saying clearly some money from the budget of Iran is going to go to the IRGC. It always has. That's no surprise. But the truth is and President Trump- I- I- well, he probably doesn't know this, but the fact is his own defense intelligence agency in 2017 testified to the Congress that very, very little money actually went to the IRGC at all. Most of the money went to the economy of Iran, which is precisely what I said and what we all said. So, the IRGC has never had a problem getting money. MARGARET, but the fact is Donald Trump keeps saying they got 150 billion dollars. A lie. He keeps saying that all of that money went to pay for it. It did not. His own defense intelligence agency says most of the money went for the economy of the country. So, you know, we have to stop dealing with questions on Donald Trump's lies and start dealing with the reality of what is going on. The fact is--

MARGARET BRENNAN: Okay.

KERRY: --that mo- the vast proportion of that money--

MARGARET BRENNAN: Yeah.

KERRY: --went to the economy of Iran and they're always going to be funding the IRGC. There was no question about that.

MARGARET BRENNAN: Right.

KERRY: And the IRGC budget has not gone up markedly as a result--

MARGARET BRENNAN: Okay.

KERRY: --of what happened with the agreement, period.

MARGARET BRENNAN: Mr. Secretary, thank you for joining us. I want to take a break because we have a report from Iran.