Much of the focus on Iran’s nuclear program has been on Tehran’s enrichment of uranium.

Negotiations between Iran and the United States over Tehran’s rapidly advancing nuclear program will move Saturday in Oman to what’s known as the “expert level” — a sign analysts say shows that the talks are moving forward rapidly.

The head of the United Nations’ nuclear watchdog has warned that Iran is “not entirely transparent” regarding its atomic program.

World powers have opened a fifth round of talks with Iran aimed at bringing the United States back into a landmark 2015 nuclear deal meant to prevent the Islamic Republic from obtaining an atomic bomb.

Iran’s nuclear program has been targeted by diplomatic efforts and sabotage attacks over the last decade, with the latest incident striking its underground Natanz facility.

(AP Photo/Ronald Zak)TEHRAN – Iran will begin to offer United Nations inspectors “less access” to its nuclear program as part of its pressure campaign on the West, though investigators will still be able to monitor Tehran's work, the U.N. atomic watchdog's chief said Sunday. In 2018, then-President Donald Trump pulled the U.S. unilaterally out of the nuclear deal, known as the Joint Comprehensive Plan of Action, saying it needed to be renegotiated. AdGrossi met earlier Sunday with Ali Akbar Salehi, the head of Iran's civilian nuclear program. In November, Iranian scientist Mohsen Fakhrizadeh, who founded the country's military nuclear program some two decades earlier, was killed in an attack Tehran blames on Israel. “Some of them may have security ramifications for Iran, whose peaceful nuclear sites have been attacked," Zarif said.

This Nov. 4, 2020, satellite photo by Maxar Technologies shows Iran's Fordo nuclear site. A resumption of 20% enrichment could see that brinksmanship return. We are ready for this and will produce (20% enriched uranium) as soon as possible.”The White House had no immediate comment and referred to a statement issued in December by Secretary of State Mike Pompeo after Iran's parliament passed a bill on increasing uranium enrichment. Under Iran's former hard-line President Mahmoud Ahmadinejad, Tehran began 20% enrichment. Israel, which under Prime Minister Benjamin Netanyahu has continued to criticize Iran's nuclear program, offered no immediate comment Saturday.

DUBAI – Iran has begun construction at its Natanz nuclear facility, satellite images released Wednesday show, just as the U.N. nuclear agency acknowledged Tehran is building an underground advanced centrifuge assembly plant after its last one exploded in a reported sabotage attack last summer. “Nothing in Iran regarding its peaceful nuclear program is being done in secret, in full keeping with the JCPOA, and as the IAEA has repeatedly confirmed,” Miryousefi said in an email. Iran maintains its nuclear program is for peaceful purposes, though Western countries fear Tehran could use it to pursue atomic weapons. Despite being one of the most-secure sites in Iran, Natanz was targeted by the Stuxnet computer virus — believed to be the creation of the U.S. and Israel — before the nuclear deal. There have been tensions with the IAEA and Iran even at Natanz, with Tehran accusing one inspector of testing positive for explosives last year.

Following the July explosion at the Natanz nuclear site, Tehran said it would build a new, more secure, structure in the mountains around the area. Ali Akbar Salehi, the head of Iran's nuclear department, last month told state television the destroyed above-ground facility was being replaced with one “in the heart of the mountains around Natanz.”Natanz hosts the country’s main uranium enrichment facility. Natanz became a flashpoint for Western fears about Iran’s nuclear program in 2002, when satellite photos showed Iran building an underground facility at the site, some 200 kilometers (125 miles) south of the capital, Tehran. In 2003, the IAEA visited Natanz, which Iran said would house centrifuges for its nuclear program, buried under some 7.6 meters (25 feet) of concrete. Still though, Iran has continued to allow IAEA inspectors full access to its nuclear facilities, including Natanz, Grossi said.

(AP Photo/Ronald Zak)BERLIN – The head of Iran's nuclear agency said Monday that the landmark 2015 deal between Tehran and world powers on his country's atomic program is struggling since the unilateral U.S. withdrawal, but is still worth preserving. The deal promises Iran economic incentives in exchange for limits on its nuclear program. The remaining world powers in the deal — France, Germany, Britain, China and Russia — have been struggling to offset re-imposed American sanctions. The ultimate goal of the JCPOA is to prevent Iran from being able to build a nuclear bomb — something Iran insists it does not want to do. It has also continued to allow IAEA inspectors full access to its nuclear facilities, which the world powers still in the deal maintain is reason enough to try and keep it in place.

This photo released Thursday, July 2, 2020, by the Atomic Energy Organization of Iran, shows a building after it was damaged by a fire, at the Natanz uranium enrichment facility some 200 miles (322 kilometers) south of the capital Tehran, Iran. A fire burned the building above Irans underground Natanz nuclear enrichment facility, though officials say it did not affect its centrifuge operation or cause any release of radiation. The Atomic Energy Organization of Iran sought to downplay the fire Thursday, calling it an incident that only affected an industrial shed. (Atomic Energy Organization of Iran via AP)TEHRAN A fire broke out early Thursday at a building above Iran's underground Natanz nuclear enrichment facility, though officials said it did not affect its centrifuge operation or cause any release of radiation. A photograph later released by the atomic energy agency showed a brick building with scorch marks and its roof apparently destroyed.