GEOFF BENNETT: Welcome to the "News Hour."

Today, across two continents, the# U.S.

confronted two very different## nuclear challenges.

For the first# time since last year's war in Iran,## U.S.

and Iranian diplomats restarted diplomacy# focused on that country's nuclear program.

AMNA NAWAZ: And for the first time today,# the U.S.

accused China of conducting a secret## nuclear test just one day after letting the final# nuclear arms control treaty with Russia expire, Nick Schifrin been covering# both stories and joins us now.

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

and Iran.# What do we know about how those talks went today?

NICK SCHIFRIN: Well, the Trump administration# has provided no readout at the moment,## but in the lead-up to these talks, we heard# from Secretary of State Marco Rubio and## the top negotiator, Steve Witkoff, that Iran# must not make any nuclear fuel domestically,## must restrict the range of its ballistic# missiles, must end its support for proxy## groups and account for highly enriched uranium# that has been missing since last summer's strikes.

Today, the U.S.

held indirect talks.

You see# Witkoff there with the president's son-in-law,## Jared Kushner, meeting Oman's foreign minister,# who then met with Iran's foreign minister, Abbas## Araghchi, who said the talks focused on nuclear# weapons and were a -- quote -- "good start."

ABBAS ARAGHCHI, Iranian Foreign Minister: We were# able to exchange our viewpoints, to express our## concerns and our interests for a possible deal# between the two sides on our nuclear question.

NICK SCHIFRIN: Araghchi said there would# be a new round of talks.

No confirmation## of that from the U.S.

side, which# for the first time included the## top U.S.

military commander from# the Middle East, a reminder, Amna,## of President Trump's threats against Iran and# that military buildup still in the region.

AMNA NAWAZ: So what do the experts tell you all of# that means for the possibility of an actual deal?

NICK SCHIFRIN: Well, that's the question# I put to Karim Sadjadpour of the Carnegie## Endowment for International Peace.

He# is very skeptical of any deal of Iran's## nuclear program, missile program, or support# for proxies, including Hezbollah and Hamas.

KARIM SADJADPOUR, Carnegie Endowment for# International Peace: The Iranian regime still## seems so intent on defying the United States# and they fear that if they give into press.. it's going to project weakness# and invite even more pressure.

Up until now Iran has shown no flexibility# on moderating its ballistic missile program,## or its regional proxies.

And# so the Iranian goal is to limit## this conversation only to nuclear and# even then to drag on the conversation.

NICK SCHIFRIN: Drag on the conversation, Amna,# so it doesn't get bombed by the United States.

A U.S.

official, though, confirms to# me that Iran is trying to reconstitute## its ballistic missile program.# Look at the before right there## and now look at the after of# a missile production facility.

Listen to distinguished scholar at# Middlebury College Jeffrey Lewis.## He's studied these kinds of images for years.

JEFFREY LEWIS, Middlebury College: We can# see those facilities in satellite images.## And so Israel attempted to destroy many# of those buildings, but now they're back.## It seems pretty clearly that Iran is well on# its way to resuming production of its missiles.

NICK SCHIFRIN: And U.S.

officials, Amna,# acknowledge that could mean Israel,## if not the U.S., try and strike those# missile production factories again in 2026.

AMNA NAWAZ: Let's turn now to those allegations,## accusations of a secret nuclear test by China.# What exactly is the U.S.

saying happened?

NICK SCHIFRIN: Yes, so, for the first time today,## the U.S.

revealed that China conducted# explosive nuclear tests, including in J.. and sought to conceal them by putting the# explosion inside an underground chamber.

That would be China's first# explosive test in some 25 years.

Now,## former senior officials told me today# that they have known about that test## for years.

So what's interesting# perhaps mostly today is the timing.## The fact that China conducted that test has not# been declassified until today, which happens to## be the day after the U.S.

let New START, the# final nuclear arms control treaty, expire.

The Trump administration and some# experts have long argued that New## START wasn't adequate because it didn't# address China's growing arsenal.

And so## today it seems to be an attempt to try# and pressure China into some kind of## three-way talks with the United States# and Russia about arms control overall.

But, honestly, Beijing has always# resisted any kind of limits on its## nuclear program while it's growing# its arsenal, says Jeffrey Lewis.

JEFFREY LEWIS: China has largely resisted# entering any kind of formal talks,## partly because their number is lower than the# U.S.

and they're in the process of catching up.

But I think at a deeper and more profound# level, it's because all of the things we want,## predictability, transparency, these are things# that China thinks are bad for it, because China## is worried that, if we find them to be predictable# and transparent, that we will be more comfortable## pushing them around in a regional security crisis# because we will know where their red lines are.

NICK SCHIFRIN: Which means no trilateral# talks with China any time soon.

And, tonight,## I spoke to former Biden senior officials and# also Republican senior arms control officials,## and both argued to me that the# U.S.

should deploy more nuclear## warheads.

And now that New START has# expired, they can do exactly that.

AMNA NAWAZ: Nick Schifrin# starting our coverage tonight.

Nick, thank you.

NICK SCHIFRIN: Thank you.