AMNA NAWAZ: Today, Iran and the U.S. confirmed that a second round of talks over Iran's nuclear program would take place this weekend in Rome.

But, at the same time, both the U.S. and Iran have hardened their negotiating positions after describing the first round as constructive.. Nick Schifrin's been following this today and joins me now.

So, Nick, let's start with the U.S. side here.

What's the U.S. position going into this second round of talks?

NICK SCHIFRIN: As you said, Amna, the mood music after the first round in Oman seemed in sync.

These were mostly indirect talks moderated by Oman's foreign minister between top presidential special envoy Steve Witkoff and Iranian Foreign Minister Abbas Araghchi.

Both sides described them as positive, as constructive, and on Monday night, Witkoff went on Sean Hannity's show and seemed to support a key Iranian demand, that Iran would allow -- would be allowed to keep its nuclear enrichment program, even if that program would be capped.

STEVE WITKOFF, U.S. Special Envoy to the Middle East: The president means what he says, which is, they cannot have a bomb.

The conversation with the Iranians will be much about two critical points, one, enrichment.

As you mentioned, they do not need to enrich past 3.67 percent.

NICK SCHIFRIN: Recall, Amna, that is the number from the 2015 Iranian nuclear deal, also known as JCPOA.

It capped Iranian enrichment at 3.67 percent, a number related to the core of Iran's reactor.

It also capped Iran's nuclear enrichment stockpile, and it guaranteed more access to Iranian facilities in exchange for sanctions relief on Iran.

Today, seven years after the U.S. withdrew, Iran enriches up to 60 percent.

That is a small step away from weapons-grade and has a total enrichment stockpile that is 25 times what it was 10 years ago.

But President Trump and his allies have long criticized the JCPOA because the caps on Iran's program expired after a number of years, and the deal allowed Iran to keep that enrichment program.

And that comes to where the U.S. is hardening its position just in the last day.

Just hours after that Hannity interview, after a Situation Room meeting with President Trump, Witkoff posted this statement on X.

He said -- quote -- "Iran must stop and eliminate its nuclear enrichment and weaponization program."

Let's keep that up for a second.

"Eliminate its enrichment program.'

That is a direct reversal of what he said on Monday night, because he's saying there Iran should not be allowed to enrich at all.

An official familiar with these negotiations tells me that -- quote -- "President Trump likes to keep people off-balance" and that the U.S. policy right now is what Witkoff posted on X.

So, at least in public, that means that the U.S., regardless of what Witkoff said previously, is demanding Iran dismantle its enrichment program.

AMNA NAWAZ: So, mixed messages there from the U.S. Where does all of that leave Iran?

NICK SCHIFRIN: Today, Araghchi criticized Witkoff's conflicting statements, and he specifically said that Witkoff's demand for Iran to dismantle that program, that was an Iranian red line.

ABBAS ARAGHCHI, Iranian Foreign Minister (through translator): We have heard contradictory and conflicting stances.

Mr. Witkoff has spoken in various ways.

The true stance will become clear at the negotiation table.

What is certain is that Iran's enrichment is a real, accepted and a factual matter, and we are prepared to build confidence regarding potential concerns, but the principle of enrichment is nonnegotiable.

NICK SCHIFRIN: Principle is nonnegotiable.

A U.S. official familiar with the negotiations tells me that they expected Iran to take a hard-line position -- quote -- "This is a negotiation.

This is how it works."

They expect those hard-line positions on every aspect of what the United States is going to prioritize in these talks, Iranian enrichment, on whether the caps on Iran's program are permanent or whether they sunset, as they did under JCPOA, and the discussion about Iranian missiles.

Iran's missile program, the largest in the Middle East, twice used to hit Israel in the last year, Witkoff says they are part of these negotiations.

AMNA NAWAZ: All right, Nick Schifrin, thanks, as always, for your reporting.

NICK SCHIFRIN: Thank you.