GENEVA, Feb 26 – US and Iranian officials are due to meet in Geneva on Thursday for a third round of indirect talks, as President Donald Trump threatens to strike Iran if a nuclear deal is not reached.The discussions come amid the largest US military build-up in the Middle East since the US-led invasion of Iraq in 2003, and with Iran vowing to respond to an attack with force.The talks are seen as a last-ditch effort to prevent a conflict, but the chances of an agreement remain unclear.While Trump has said he prefers to solve the crisis through diplomacy, he has also said he is considering a limited strike on Iran to pressure its leaders to accept a deal.The president, however, has done little to explain what he is demanding in the negotiations and why there could be the need to take military action now, eight months after the US bombed Iranian nuclear facilities during a war between Israel and Iran.Iran has rejected the US demand to stop the enrichment of uranium in its territory, but there have been indications that it is prepared to offer some concessions about its nuclear programme.As in the previous two rounds of discussions, which were mediated by Oman earlier this month, the Iranian delegation will be led by Foreign Minister Abbas Araghchi, while the US will be represented by special envoy Steve Witkoff and Trump’s son-in-law, Jared Kushner.In recent weeks, the US has sent thousands of troops and what Trump has described as an “armada” to the region, including two aircraft carriers along with other warships, as well as fighter jets and refuelling aircraft.Trump first threatened to bomb Iran last month as security forces brutally repressed anti-government protests, killing thousands of people. But since then, his focus has turned to Iran’s nuclear programme, which has been at the centre of a long-running dispute with the West.For decades, the US and Israel have accused Iran of trying to secretly develop a nuclear weapon. Iran insists its programme is only for peaceful purposes, though the country is the only non-nuclear-armed state to have enriched uranium at near weapons-grade level.