John: Good evening.

I'm John yang.

Iran is bracing for global sanctions over its nuclear program to go back in place.

The measures threaten to cripple Iran's economy, their currency is at a record low and ordinary Iranians struggle to get the food they need to survive.

The un security council rejected a last ditch effort to delay the sanctions after negotiations with European nations failed to reach a deal.

Barring some sort of last-minute diplomatic breakthrough, the renewed sanctions will freeze Iranian assets abroad, penalize any development of Iran's ballistic missile program and ban the sale or transfer of conventional weapons.

Frontline correspondent Sebastian walker conducted an exclusive interview earlier this week with Ali larijani, head of Iran's surpeme national security council.

He previewed for you Iran's reaction to these sanctions going back in place, but listen to what he had to say.

>> It is conditional.

Ohn: Tell us more.

Why is this so significant?

Sebastian: He is the second cherry of supreme nationals are pretty counsel in Iran which has the say of a foreign policy decisions, head of the security apparatus, and also strategy over the nuclear program.

He's essentially the chief negotiator.

What he says is extremely significant.

This is a very rare conversation.

This is the first time that he has spoken to foreign media since his appointment.

It's also the first interview that he's given since the 12-day 12-day conflict with the U.S.

And Israel.

And the timing of this just in the lead up to everything that we've heard at the un, and this deadline for the sanctions to come back, made this a very, very interesting conversation to have.

John: You also asked him to react to the U.S.

Claims that that attack by the United States and Israel obliterated their nuclear program.

Sebastian: President trump has said that the enrichment facilities targeted were completely and totally obliterated.

Is he right?

[speaking another language] Ebastian: What is your assessment of the extent to which these sites have been damaged and how much this has set back Iran's nuclear program?

>>[Speaking another language] Ohn: What was your take away from that answer?

Sebastian: Well, this is obviously at the heart of what's going on with this question over whether un inspectors should be allowed back in or not.

Iran wants to preserve as much mystery as they can about the extent of the damage.

This is what everyone wants to know.

Did these strikes succeed in degrading Iran's enrichment facilities?

Were the U.S.

Strikes on natanz, fordow, esfahan sufficient enough to set back the program?

We asked for access to these facilities.

We were pushing as hard as we possibly could on the ground to get any filming done of any of the strikes were the U.S.

Missiles hit.

We were told that was impossible.

And you heard from Mr.

Larijani there that they don't think that the bombed sites should be open to un inspectors.

This is something that he said really is conditional on the sanctions not being reimposed, he was saying, essentially, if these sanctions come back, then they will end their participation with the iaea.

And you're seeing signs of that already.

Iran has recalled its ambassadors from Germany, France, the uk for consultations.

He warned about the consequences of these actions and that Iran could withdraw from these negotiations as a result.

I mean, we pushed him on a number of questions that I think international observers have about the impact of these attacks.

We asked him, where is Iran's stockpile of highly enriched uranium?

More than 400 kilos of Heu that Iran says is buried under rubble.

International observers want to know where that is.

And we asked him for information about that.

None was forthcoming.

So again, the takeaway overall is that Iran really is trying to kind of preserve whatever mystery it can about the extent of the damage.

That's one of the few tools that they really have left after this devastating war that's taken place.

John: You also asked him about the possibility of more U.S.

Attacks.

Sebastian: What's your message to the trump administration if there are more attacks?

What will be the consequences of that?

>> [Speaking another language] John: Do you get the sense that they're worried about more attacks, either from the united States or from Israel?

Sebastian: I think there's definitely a worry about that, the attacks.

I mean, we were able to travel around the country to places that were targeted.

We didn't see the U.S.

Strike sites, but we able visit locations where Israel had eliminated some of Iran's leading nuclear scientists.

Places in Tehran that had been bombed, apartment buildings.

There's a real apprehension on the part of Iranians that we met that more strikes could be coming down the road.

There was alarm about how much had happened during this war.

The 12-day conflict really showed Iran's weaknesses to a lot of ordinary people that these scientists could be eliminated so effectively.

And I think spending time in the country, while we weren't able to really have a kind of truly authentic engagement with Iranians that we met, you're very highly monitored, controlled everywhere you go.

It's very challenging as a reporter to report from Iran.

But there is a sense that these strikes have really kind of had a huge impact.

The Iranian currency is at a record low.

The news of the sanctions coming coming back I think his -- sanctions coming back I think is incredibly worrying for a lot of ordinary Iranians.

And it's just something that I think is we're really now at a point where anything could happen next.

The sanctions coming back in puts Iran into a place where the engagement with the international community is now unclear.

You heard from Mr.

Larijani there saying that they are going to withdraw from participation with the iaea.

And I think that begs the question, what are going be the consequences of that?

What are the U.S.

And Israel going to do next?

John: Frontline correspondent, Sebastian walker.

Thank you very much.

Sebastian's exclusive interview will be part of a coupling --