Iran has advanced its nuclear program to where it will be able to produce weapons-grade fuel in two to four months, nuclear experts and former United Nations inspectors said.
The new assessments feed growing alarm in the U.S., Europe and Israel that efforts to deny Tehran a nuclear-weapons capability could be rendered futile by as early as next summer.
Israeli Prime Minister Benjamin Netanyahu told the U.N. General Assembly last month that the international community needed to be prepared to strike Iran’s nuclear sites by the summer.
Iran denies it is pursuing atomic weapons and says its nuclear work is solely for civilian purposes. U.S. officials said they believe Iran’s Supreme Leader Ayatollah Ali Khamenei has yet to make the political decision to acquire a nuclear bomb.
The state of Iran’s nuclear program has become a major foreign-policy issue in this year’s U.S. presidential election. Republican candidate Mitt Romney has charged President Barack Obama with being soft on confronting Iran. The White House said its sanctions aimed at pressing Iranian leaders to bend to international demands have fueled a 40% fall in the value of the Iranian currency in the past two weeks.
The Institute for Science and International Security, an independent research institute in Washington with former U.N. inspectors on its staff, concluded in a report this week that Iran could produce enough highly enriched uranium for one atomic bomb, about 25 kilograms, in two to four months using its largest uranium-enrichment facility near the city of Natanz.
The ISIS report offered a faster timeline than Mr. Netanyahu presented to the U.N. on Sept. 27 because of Tehran’s growing stockpile of higher-enriched uranium and its expanding numbers of centrifuge machines. The Israeli leader said Iran is expected to have acquired enough higher-enriched uranium by spring or summer to begin conversion to weapons grade. He said Iran then could construct its first nuclear bomb within several weeks or months.
ISIS bases its conclusions almost solely on information released by the U.N.’s nuclear watchdog, the International Atomic Energy Agency. The IAEA said in its most recent report in August that Tehran had doubled its capacity to produce 20% enriched uranium at its underground facility near the holy city of Qom. But the IAEA didn’t offer a timeline for when Iran might be able to produce weapons-grade fuel.
The think tank said Tehran could combine its stockpiles of low-enriched and higher-enriched uranium to make a dash for weapons-grade fuel, which is around 90% purity. The Iranians could do that by synchronizing the enrichment of these two grades of uranium and cutting out some intermediary steps that slow the process, ISIS said.
“Growth in the stock of near 20% [purity] reduces the time to break out,” ISIS said in its report.
Iran has a stockpile 91.4 kilograms of uranium enriched to 20% purity, according to the IAEA. An additional 25 kilograms of the material is committed for conversion into fuel rods for Tehran’s research reactor.
ISIS said its faster estimates for Iran acquiring the highly enriched uranium would require Tehran to use its total stockpile of 20% enriched uranium.
The institute played down Mr. Netanyahu’s assertion that Iran could quickly convert the weapons-grade fuel into a usable atomic bomb. “Iran would need many additional months to manufacture a nuclear device suitable for underground testing and even longer to make a reliable warhead for a ballistic missile,” the report said.
U.S. officials believe Iran would need 12 to 18 months to build an atomic weapon if Mr. Khamenei gives the order. The U.S. intelligence community concluded in a controversial 2007 report that Tehran had ended a structured program to build an atomic bomb four years earlier, though some research is believed to have continued.
IAEA officials have said recently that they believe the suspected head of Iran’s nuclear-weapons studies, scientist Mohsen Fakhrizadeh, reopened a scientific office last year. And the U.N. agency has been pressing Iran, so far unsuccessfully, to allow it to visit a military facility south of Tehran, called Parchin, where the IAEA believes nuclear-weapons related tests had occurred.
The Obama administration has voiced concerns about the threat posed by Iran’s production of higher-enriched uranium. But U.S. officials have stressed that the IAEA would detect any moves by Iran to reconfigure their centrifuge machines to begin producing weapons-grade fuel.
IAEA inspectors visit the sites in Natanz and Qom around twice a month. The agency also has cameras monitoring the sites.
Iran, however, has indicated in recent months that it may further limit its cooperation with the IAEA.
The head of Iran’s Atomic Energy Organization, Fereydoun Abbasi-Davani, charged the Vienna-based agency last month with trying to sabotage Iran’s uranium-enrichment facilities by cutting off electricity supply.
Iran also has accused the IAEA of being complicit in the murders of five Iranian nuclear scientists over the past five years and spying for Western countries. The IAEA has denied these charges.
“If the IAEA has to end or limit these inspections, there could be a serious problem,” said Olli Heinonen, a former chief weapons inspector at the agency, during a presentation on Tuesday in Washington.
Both Mr. Heinonen and ISIS said that the underground facility at Qom is playing an increasingly central role in Iran’s nuclear-fuel production. The facility is buried deep underground and seen as potentially impervious to attacks.
Currently, the Qom site is seen as incapable of quickly producing highly enriched uranium because of the dearth of centrifuges currently operating there. But the IAEA said in August that over 2,000 machines could be operating there shortly.
Still, ISIS said in the report that it doesn’t expect Iran to “break out” in the next year, because of the high likelihood that such moves would be detected by the IAEA and lead to an American or Israeli military strike.
“Iran’s current trajectory at [the Qom facility] is increasing the chance of a military confrontation, particularly given growing concern about the relatively short breakout time,” ISIS said.