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Researchers have provided new insights to VOA about Iranian scientific work that seems to have influenced a revised U.S. assessment that Tehran is better positioned to weaponize its nuclear program.
An unclassified assessment sent to Congress in July by the Office of the Director of National Intelligence (ODNI) said that since 2020, Iran has "undertaken activities that better position it to produce a nuclear device, if it chooses to do so."
While the one-page assessment does not elaborate on those activities, reports published by U.S. news sites The Wall Street Journal and Axios in June , July and August cited unnamed U.S. and Israeli officials as expressing concern that Iran was engaged in computer modeling and metallurgical research that is useful in building nuclear weapons. Those reports did not elaborate on the nature of the research or Iran's motivation for conducting it.
The ODNI assessment omitted an assertion, made in its 2023 report to Congress, about Iran "not currently undertaking the key nuclear weapons development activities that would be necessary to produce a testable nuclear device."
U.S. House Intelligence Committee chairman Michael Turner used a Sunday interview with TV network CBS to highlight the recent news reports about Iran's potential nuclear weaponization-related work. He described the reports as noting a "possibility" that Iran could declare itself to be a nuclear-armed state by the end of this year.
Iran long has insisted that it does not seek nuclear weapons. But the latest ODNI assessment said there has been a "notable increase this year in Iranian public statements about nuclear weapons, suggesting the topic is becoming less taboo."
ODNI declined to comment when asked by VOA about the specific types of Iranian activities that it examined to develop its latest assessment.
An ODNI spokesperson said the U.S intelligence community "remains focused on monitoring Iran's nuclear program, and we assess that the Supreme Leader [Ayatollah Ali Khamenei] has not made a decision to resume the nuclear weapons program that Iran suspended in 2003."
Iran's U.N. mission in New York did not respond to a VOA request, emailed on August 13, for comment on the nature of the Iranian scientific research that apparently prompted the revised ODNI assessment of Tehran's nuclear work.
One researcher who spoke to VOA, American physicist David Albright, said ODNI may have based that revised assessment at least in part on Iranian work in "computer modeling couched in civil research efforts" that would benefit a nuclear weapons program.
Albright, president of the Washington-based nonprofit Institute for Science and International Security, said he found references in recent Iranian scientific reports to the use of software and computer codes for running simulations that are helpful in nuclear weapon design.
The physicist, who has testified numerous times before Congress about his studies of secret nuclear weapons programs around the world, said his team reviewed more than 150 Iranian scientific reports published in recent years and obtained from open sources. Some of those reports were published this year, he said.
"The modeling work involves simulations of shock waves from explosively projecting pieces of metal against another solid metal. This modeling is necessary to understand how a nuclear explosion would take place," Albright said.
He added that the Iranian scientific reports do not describe simulations of shock waves hitting the core of a nuclear weapon. "It is not obvious from reading the documents that the authors are working on the codes for nuclear weapons," he said.
Albright said the Iranian scientists involved the recent computer modeling likely are hiding the weaponization goals of their work as part of a pattern of deceptive behavior that he found in his past reviews of two sets of secret Iranian nuclear documents. He said one set of documents was from 2006 and obtained by him and London's The Times newspaper from an unnamed source the following year, while the other set was stolen by Israel from Iran's nuclear archives in 2018 and shared with him by Israeli officials.
Describing the two sets of documents in his 2021 book Iran's Perilous Pursuit of Nuclear Weapons, Albright said they indicate that after Tehran shut down a nuclear weapons program in 2003 - as determined by the International Atomic Energy Agency - Iranian officials decided to keep some of it going by assigning research projects to Iranian universities.
As part of that effort, the Iranian researchers employed cover stories to portray their work as civilian in nature and to obscure their links to officials involved in nuclear work, he wrote.
Another researcher, nuclear policy program senior fellow Ariel Levite of the Washington-based Carnegie Endowment for International Peace, told VOA that Iran appears to have restarted research, after a pause of several years, to remove the last knowledge gap toward weaponizing a nuclear program. He noted that Iran already has made major strides in amassing nuclear weapons-grade enriched uranium and developing missiles that can carry nuclear warheads.
Levite, a former senior Israeli nuclear energy and defense official, said there are three ways to interpret Iran's motivation for pursuing such research: a warning to the U.S. and Israel that it stands ready to take the final steps toward nuclear weaponization, an internal decision to relax the Iranian supreme leader's 2004 decree or fatwa against developing nuclear weapons, or an attempt by overzealous Iranian advocates of nuclear weaponization to push the limits of the decree.
"We are left in a guessing game," Levite said. "If I had to guess the motivation, I would say it is a mixture of all three."
Albright said Iran's work in computer modeling would reduce the number of experiments needed to test a nuclear device and would give Iran greater confidence that such a device would work.
"That can save them time in building a bomb, but we don't know enough about their program to be able to quantify it. Overall, they have done enough that they can certainly do it in less than six months," he said.
Levite said he does not believe Iran's latest scientific research gives it the ability to produce its first rudimentary nuclear bomb in less than three to six months.
"But given how far along Iran's nuclear program already is, our margin for error in assessing its capabilities and intentions is shrinking while the Iranian leverage that comes with such an advanced nuclear threshold status is growing," he said. "Iran might be poised to shorten further the timeframe toward nuclear weapon acquisition."