US, Iranian delegations back for resumed nuclear talks in Geneva: AFP

• Amid a 15-day ultimatum from President Trump, US and Iranian negotiators returned to Geneva for "intense" talks, with the US reportedly demanding the total dismantling of three major nuclear sites (Fordow, Natanz, and Isfahan) and the transfer of all enriched uranium to American custody.
• The negotiations are unfolding as the US completes its largest military buildup in the region since 2003, featuring two carrier strike groups—led by the USS Abraham Lincoln and the USS Gerald R. Ford—stationed to provide "flexible options" should diplomacy fail to reach a "zero enrichment" agreement.

US and Iranian officials returned Thursday evening to the Geneva location where their high-stakes indirect nuclear talks were due to resume, a diplomatic source told AFP.

Convoys of cars belonging to US and Iranian diplomatic missions arrived back at the residence of Oman's ambassador before 17:00 GMT following a break of several hours after an initial round of discussions on Thursday morning.

The talks are a last-ditch bid to avert war under the shadow of the biggest American military build-up in the Middle East in decades.

The Oman-mediated discussions follow repeated threats from Donald Trump to strike Iran, with the US president last Thursday giving Tehran 15 days to reach a deal.

While Iran has insisted the discussions focus solely on its nuclear programme, the US wants Tehran's missile programme and its support for armed groups in the region curtailed.

Oman's Foreign Minister Badr Albusaidi said after the morning session that the two sides expressed "unprecedented openness to new and creative ideas and solutions".

UN nuclear chief Rafael Grossi joined the negotiations.

The Wall Street Journal reported on Thursday that Trump's negotiating team would demand that Iran dismantle its three main nuclear sites and hand over all its remaining enriched uranium to the United States.

Iran's President Masoud Pezeshkian insisted ahead of the talks that the Islamic republic was not "at all" seeking a nuclear weapon.

As part of the dramatic US build-up, the USS Gerald R. Ford, the world's largest aircraft carrier, sent to the Mediterranean this week, left a naval base in Crete on Thursday.

Washington currently has more than a dozen warships in the Middle East: one aircraft carrier -- the USS Abraham Lincoln -- nine destroyers and three other combat ships.

It is rare for there to be two US aircraft carriers, which carry dozens of warplanes and are crewed by thousands of sailors, in the region.

The developments follow massive protests in Iran that rights groups say saw thousands of demonstrators killed.