Iran and the United States held in-depth negotiations in Oman over Tehran's rapidly advancing nuclear program on Saturday, talks that likely hinged on the Islamic Republic's enrichment of uranium.Related video above: Trump said Iran 'cannot have a nuclear weapon'The talks ran for several hours in Muscat, the mountain-wrapped capital of this sultanate on the eastern edge of the Arabian Peninsula.A person close to Steve Witkoff, the U.S. special envoy to the Middle East, acknowledged that the meeting had started and later ended. The source spoke on condition of anonymity to discuss the closed-door talks. Iranian state television also reported their conclusion.However, neither Iranian Foreign Minister Abbas Araghchi nor Witkoff offered any immediate specifics or details on the talks.Araghchi arrived Friday in Oman and met with Omani Foreign Minister Badr al-Busaidi, who has mediated the two previous rounds of talks in Muscat and Rome. Araghchi then visited the Muscat International Book Fair surrounded by television cameras and photojournalists. Video late Saturday morning showed Araghchi heading to the talks.Witkoff was in Moscow on Friday meeting with Russian President Vladimir Putin. He arrived Saturday to Oman, where the talks were held, a source familiar with Witkoff's travels told The Associated Press, speaking on condition of anonymity to discuss the negotiations.Meanwhile Saturday, a major explosion rocked a port in southern Iran just after the talks began, killing four people and injuring more than 500 others. Authorities offered no immediate cause for the blast, which appeared to have been caused by a highly combustible material 맥스카지노� though officials ruled out its oil and gas industry. The private security firm also linked to a shipment of a chemical ingredient used to make missile propellant to the port as well.Nuclear talks come after decades of tensionsThe talks seek to limit Iran맥스카지노�s nuclear program in exchange for the lifting of some of the crushing economic sanctions the U.S. has imposed on the Islamic Republic closing in on a half-century of enmity.U.S. President Donald Trump has repeatedly threatened to unleash airstrikes targeting Iran맥스카지노�s program if a deal is not reached. Iranian officials increasingly warn that they could pursue a nuclear weapon with their stockpile of uranium enriched to near weapons-grade levels.Iran's 2015 nuclear deal with world powers did limit Tehran's program. However, Trump unilaterally withdrew from it in 2018, setting in motion years of attacks and tensions. The wider Middle East also remains on edge over the Israel-Hamas war in the Gaza Strip.Trump, traveling to Rome for the funeral of Pope Francis, again said that he hoped negotiations would lead to a new nuclear deal. However, he still held out the possibility of a military strike if they did not.맥스카지노�The Iran situation is coming out very well,맥스카지노� Trump said on Air Force One. 맥스카지노�We've had a lot of talks with them, and I think we're going to have a deal. I'd much rather have a deal than the other alternative. That would be good for humanity."He added, 맥스카지노�There are some people that want to make a different kind of a deal 맥스카지노� a much nastier deal 맥스카지노� and I don맥스카지노�t want that to happen to Iran if we can avoid it.맥스카지노� Talks turn to expertsWhile Araghchi and Witkoff were again expected to speak through the Omanis, experts on both sides were also to begin negotiating details of a possible deal.From the Iranian side, Iranian Deputy Foreign Minister Majid Takht-e Ravanchi was to lead Tehran맥스카지노�s expert team, said Mohammad Golzari, an Iranian government official. Takht-e Ravanchi took part in the 2015 nuclear talks.The U.S. technical team, which is expected to arrive in Oman on Friday, was to be led by Michael Anton, the director of U.S. Secretary of State Marco Rubio맥스카지노�s policy planning staff. Anton doesn't have the nuclear policy experience of those who led Washington맥스카지노�s efforts in the 2015 talks.Iran has insisted that keeping its enrichment is key. But Witkoff has muddied the issue by first suggesting in a television interview that Iran could enrich uranium at 3.67%, then later saying that all enrichment must stop. The demand that all enrichment stop also has been repeated by Rubio.However, Iranians remain hopeful that the talks could be successful, as the Iranian rial has rebounded from historic lows during which it took more than 1 million rials to buy $1.맥스카지노�It맥스카지노�s OK to negotiate, to make the nuclear program smaller or bigger, and reach a deal,맥스카지노� Tehran resident Farzin Keivan said. 맥스카지노�Of course, we shouldn맥스카지노�t give them everything. After all, we맥스카지노�ve suffered a lot for this program.맥스카지노�___Amir Vahdat contributed to this report from Tehran, Iran.___The Associated Press receives support for nuclear security coverage from the Carnegie Corporation of New York and Outrider Foundation. The AP is solely responsible for all content.