They will be the highest-level discussions between the foes since an international agreement on Iran's nuclear programme crumbled after Trump pulled out in 2018 during his first term in office.
Trump's special envoy Steve Witkoff and Iranian Foreign Minister Abbas Araghchi are set to lead the discussions behind closed doors in Muscat, the capital of Oman, which has long played a mediating role between Iran and Western countries.
Iranian state TV said that after his delegation arrived in Muscat on Saturday morning Araghchi met with Omani officials.
Hours before the talks were due to begin Trump told reporters aboard Air Force One: "I want Iran to be a wonderful, great, happy country. But they can't have a nuclear weapon."
Trump had made a surprise announcement last Monday that the talks would take place.
Iranian supreme leader Ayatollah Ali Khamenei's adviser Ali Shamkhani said Tehran was "seeking a real and fair agreement", adding that "important and implementable proposals are ready".
If Washington showed goodwill, the path forward would be "smooth", he said on social media platform X.
The format for the talks has not been confirmed, with the United States calling them direct talks but Iran insisting on an intermediary.
According to Iranian news agency Tasnim, the delegations will start indirect negotiations after a meeting with Omani Foreign Minister Badr bin Hamad Al Busaidi.
The talks are expected to begin in the afternoon with Busaidi as intermediary, Tasnim added.
AzVision.az
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