AMNA NAWAZ: In Geneva today,# the U.S.

and Iran concluded## a third round of indirect and at times# direct negotiations.

Iranian officials## announced that technical talks will begin# on Monday with the U.N.

nuclear watchdog.

That suggests some possible# progress, as the United States## deploys the largest military presence to# the Middle East in more than 20 years.

Stephanie Sy begins our coverage.

STEPHANIE SY: In Geneva today,## U.S.

envoy Steve Witkoff and President# Trump's son-in-law Jared Kushner held## crucial negotiations with Iran, at first indirect# through Oman's foreign minister and then direct.

Iran's Foreign Minister Abbas# Araghchi signaled positive momentum.

ABBAS ARAGHCHI, Iranian Foreign# Minister: We made a very good## progress.

We were able to define the# main ele.. and we discussed about those elements.

Of# course, there are still differences, but in## most of the cases we have at least a general# understanding how to resolve those questions.

STEPHANIE SY: That despite an official# brief on the talks telling "PBS News## Hour" that the U.S.

demanded Iran destroy# its three main nuclear enrichment sites,## Fordow, Isfahan and Natanz, the same sites# struck by American bombers last summer.

And the officials said the U.S.

team demanded# Iran get rid of its highly enriched uranium,## which Iran says was buried during the# strike on the Fordow enrichment plant.## Iran announced that technical talks would# start on Monday in Vienna and a fourth## round of political negotiations# would be scheduled in a week.

DONALD TRUMP, President of the United# States: They want to start all over## again and at this moment again# pursuing their sinister ambiti.. STEPHANIE SY: This week, in# his State of the Union address,## President Trump vowed that he would not# allow Iran to obtain a nuclear weapon.

DONALD TRUMP: My preference is to solve# this problem through diplomacy.

But one## thing is certain.

I will never allow the# world's number one sponsor of terror,## which they are by far, to have a# nuclear weapon.

Can't let that happen.

STEPHANIE SY: And President Trump# went further than public intelligence## estimates and accused Iran of pursuing# intercontinental ballistic missiles.

DONALD TRUMP: They have already developed missiles# that can threaten Europe and our bases overseas,## and they're working to build missiles that# will soon reach the United States of America.

STEPHANIE SY: Tehran has repeatedly# denied ever seeking nuclear weapons and## has long claimed its uranium enrichment# activities are for civilian purposes.

Just before the talks, Araghchi# reiterated that Iran's right to## nuclear enrichment is nonnegotiable and# vowed retaliation if the U.S.

attacks.

ABBAS ARAGHCHI: We are ready to remove# concerns, but we are not ready to give## up our rights for peaceful use of# nuclear technology.

If, God forbid,## the U.S.

decides to attack us, then their bases# in the region would be a legitimate target.

STEPHANIE SY: Wartime preparations are ramping# up.

Today, the largest U.S.

aircraft carrier,## the Gerald Ford, left the Greek island# of Crete in the Eastern Mediterranean,## adding to the Abraham Lincoln and its# accompanying ships already in the Arabian Sea.

Fighter jets and support aircraft, as well as# air defense, are deployed across the region.## And for the first time outside of a training# mission, the U.S.

has deployed F-22 fighter## jets to Israel.

Israel has made it clear# it would respond to any Iranian attack,## even if it follows a U.S.

strike# with a larger war than last summer.

BENJAMIN NETANYAHU, Israeli Prime Minister# (through translator): I passed on and## clarified to the regime of the ayatollahs that,# if they make perhaps the gravest mistak.. history and attack the state of Israel, we will# respond with a force they cannot even imagine.

STEPHANIE SY: The ongoing talks could be a last# chance for diplomacy before a potential war,## a moment that could define the# future of peace in the Middle East.

For the "PBS News Hour," I'm Stephanie Sy.