The talks are the first diplomatic encounter between the United States and Iran since Washington joined Israel's conflict against the Islamic republic in June with strikes on nuclear sites.
Iranian and US officials have arrived in Oman's capital Muscat for highly anticipated talks on Iran's nuclear programme, as tensions remain high following deadly anti-government protests in Iran.
The talks are the first such encounter between the two sides since the US joined Israel's 12-day conflict against the Islamic Republic in June with strikes on nuclear sites.
US President Donald Trump's Middle East envoy Steve Witkoff and Iranian Foreign Minister Abbas Araghchi are leading their delegations at the negotiations in the Gulf sultanate, which has periodically acted as a mediator between the countries.
Ahead of the talks, Araghchi said Tehran will take the "approach of using diplomacy to secure Iran's national interests" during a meeting in Muscat with Badr al-Busaidi, foreign minister of Oman.
Meanwhile, he added that his country maintains "full readiness to defend the country's sovereignty and national security against any excessive demands or adventurism" by the United States, as Trump has also refused to rule out military action against Tehran.
The US delegation intends to explore "zero nuclear capacity" for Iran, White House Press Secretary Karoline Leavitt said, warning that Trump had "many options at his disposal aside from diplomacy".
"They're negotiating," Trump said of Iran on Thursday.
"They don't want us to hit them, we have a big fleet going there," he added, referring to the aircraft carrier group he has repeatedly called an "armada".
The meeting comes just under a month after the peak of a wave of nationwide protests in Iran sparked by persistent hyperinflation and high cost of living which turned into demonstrations against the Tehran regime.
The protests were repressed with an information blackout and unprecedented crackdown that has resulted in the deaths of as many as 30,000 people, according to insiders in Iran and human rights groups.
Trump initially threatened military action against Tehran, telling demonstrators "help is on its way" but has so far refrained from an outright intervention.
Scope of talks remains unclear
The scope, nature and participants in the talks remain unclear, just hours before they were due to begin in Muscat.
There had been tensions in the run-up to the talks over whether the meeting should also include regional countries and address Tehran's support of proxies and its ballistic missile programmes, two US concerns that Iran resisted. Tehran has maintained that these talks will only be on its nuclear programme.
US Secretary of State Marco Rubio said talks needed to include all those issues. “I think in order for talks to actually lead to something meaningful, they will have to include certain things, and that includes the range of their ballistic missiles,” Rubio told journalists Wednesday.
“That includes their sponsorship of terrorist organisations across the region. That includes the nuclear programme, and that includes the treatment of their own people.”
With the aircraft carrier USS Abraham Lincoln and other warships in the region along with more fighter jets, the US now likely has the military firepower to launch an attack if it wanted.
Meanwhile, Gulf Arab nations fear an attack could spark a broader regional war, as this week US forces have shot down an Iranian drone near the aircraft carrier while Iran attempted to stop a US-flagged ship with speedboats in the Strait of Hormuz.