Of all the pressing issues in the volatile Middle East, the most pressing for the Biden administration will be Iran’s controversial nuclear program. Joe Biden pledged to rejoin the landmark nuclear deal negotiated between Iran and the six major world powers in 2015. “If Iran returns to strict compliance with the nuclear deal, the United States would rejoin the agreement as a starting point for follow-on negotiations,” he wrote in an op-ed for CNN in September 2020.
But rejoining the nuclear agreement will not be easy. The Islamic Republic continued to comply with its obligations for more than a year after President Donald Trump abandoned it in May 2018. In July 2019, Tehran began breaching the agreement. Iran’s breaches had been largely incremental and calibrated until the assassination of Mohsen Fakhrizadeh, a top nuclear scientist, on November 27, 2020.
- In July 2019, Iran surpassed limits on its stockpile of low-enriched uranium. A week later, it increased enrichment from 3.67 percent to 4.5 percent.
- In September 2019, it began using advanced centrifuges to enrich uranium.
- In November 2019, it began enriching uranium at the underground Fordo facility.
- In November 2019, it surpassed the limits on its stockpile of heavy water.
- In September 2020, its stockpile of low-enriched uranium reached 2,105 kilograms (2.3 tons), or about 10 times more than the limit set by the nuclear deal.
- In November 2020, its stockpile of low-enriched uranium reached 2,443 kilograms (2.7 tons), or about 12 times more than the limit set by the nuclear deal. A week later, it began enriching using 174 advanced centrifuges, the IR-2Ms.
- In January 2021, it began enriching uranium at 20 percent at Fordo.
- In February 2021, Iran suspended IAEA snap inspections of undeclared nuclear sites.
- In March 2021, Iran began enriching uranium at the Natanz facility with advanced IR-4 centrifuges.
- In April 2021, Iran began testing advanced IR-9 centrifuges and enriching uranium up to 60 percent.
Taken together, Iran’s so-called breakout time – the time needed to enrich enough uranium for one nuclear bomb – has shortened from one year to about three months, non-government nuclear experts estimated.
On December 1, 2020, three days after the Fakhrizadeh assassination, Iran's parliament, which is dominated by conservatives, enacted legislation demanding that the government immediately resume enriching uranium to 20 percent, a step that could bring Tehran closer to attaining fuel for a bomb. The nuclear deal stipulated that Tehran could only enrich uranium to 3.67 percent. On December 3, Iran told the International Atomic Energy Agency (IAEA) that it would quadruple the number of advanced centrifuges at an underground facility at Natanz.
In January 2021, Iran resumed enriching uranium to 20 percent at Fordo, an underground nuclear facility. The IAEA warned that Iran was “quite rapidly” enriching uranium at 20 percent. “It is clear that we don’t have many months ahead of us,” IAEA director Rafael Grossi said on January 11. “We have weeks.” By January 28, Iran had enriched 17 kg (37.5 lbs) of 20 percent enriched uranium and said that it planned to produce 120 kg (44 lbs) by the end of the year.
Iran also started research on metal-based fuels that could potentially be used as the core of a nuclear weapon. Britain, France and Germany were "deeply concerned" by the move. "Iran has no credible civilian use for uranium metal," the three governments said in a joint statement. "The production of uranium metal has potentially grave military implications." The following is a rundown of Iran’s breaches and assessments by the IAEA on Iran’s nuclear program.
Timeline of IAEA reports
Aug. 30, 2019: An IAEA safeguards report confirmed that Iran had begun to enrich uranium to 4.5 percent, beyond the 3.67 percent limit stipulated in the JCPOA. The agency also verified that Iran’s stockpile of low-enriched uranium exceeded the 300 kg limit. Iran continued to adhere to other aspects of the deal and allowed inspectors access to all sites that they needed to visit. But the report implied that Iran’s cooperation could use improvement. “Ongoing interactions between the Agency and Iran...require full and timely cooperation by Iran. The Agency continues to pursue this objective with Iran,” said the report.
Sept. 25, 2019: The IAEA found that Iran had breached the JCPOA again by using advanced centrifuges to enrich uranium. The watchdog “verified that all of the (centrifuge) cascades already installed in R&D lines 2 and 3 ... were accumulating, or had been prepared to accumulate, enriched uranium.” Each cascade could include up to 20 centrifuges. The JCPOA only allowed Iran to use some 5,000 of its first-generation IR-1 centrifuges to enrich uranium. Advanced centrifuges were supposed to only be used in small numbers for research purposes.
Nov. 11, 2019: In a quarterly report, the IAEA said that Iran had breached the 2015 nuclear deal by increasing its stockpile of enriched uranium. The watchdog also reported that its inspectors had found traces of uranium “at a location in Iran not declared to the agency.” The IAEA confirmed Iran had started enriching uranium at the underground Fordo facility. The JCPOA had banned uranium enrichment at the site until 2031.
Nov. 18, 2019: The IAEA confirmed that Iran had breached the 130 metric ton limit on heavy water set by the JCPOA. Heavy water allows unenriched uranium to be used as a fuel in specially designed nuclear reactors. Heavy water reactors also produce plutonium as a waste fuel, which can then be reprocessed for use in plutonium bombs.
March 3, 2020: The IAEA released two reports that criticized Iran for violations of the JCPOA. Iran had tripled its stockpile of low- enriched uranium over the previous three months, it said in one report. It shortened the breakout time to produce enough fissile material for a nuclear weapon, although the IAEA did not find evidence that Iran had taken steps to produce a bomb. In the second report, the IAEA condemned Iran’s refusal to grant inspectors access to three sites of interest. The report said that it found evidence from early July 2019 that was consistent with efforts to “sanitize” part of an unnamed location to obscure nuclear material.
March 3, 2020: The IAEA said that Iran had refused to grant inspectors access to three sites of interest. The sites were suspected to have been part of the Iran’s nuclear program in the early 2000s. The watchdog believed that Iran had tried “to sanitize part of the location” to obscure its past nuclear activities. “Iran is curtailing the ability of the agency to do its work,” IAEA Director General Rafael Grossi said.
June 5, 2020: The IAEA said that Iran’s stockpile of enriched uranium had grown far above the amount permitted by the JCPOA. Iran possessed 1,571.6 kg of low enriched uranium, a 50 percent increase since February. Its stockpile of heavy water remained slightly above the 130 metric ton limit set by the JCPOA.
June 5, 2020: Iran blocked IAEA inspectors from accessing two sites, the U.N. watchdog reported. The agency said that the sites may have been used for the storage and explosive testing of undeclared nuclear materials in the early 2000s. “The Agency notes with serious concern that, for over four months, Iran has denied access to the Agency…to two locations and, for almost a year, has not engaged in substantive discussions to clarify Agency questions related to possible undeclared nuclear material and nuclear-related activities in Iran,” the report said.
June 19, 2020: The IAEA Board of Governors passed a resolution—25 to two, with seven abstentions—calling on Iran to fully cooperate with an investigation into its past nuclear work after more than a year of stonewalling. Iran had denied inspectors access to two suspect sites where it was suspected of storing undeclared nuclear material The resolution was the first formal challenge of Iran in eight years from the IAEA Board of Governors.
Aug. 26, 2020: The IAEA and Iran released a joint statement which said that Iran agreed to provide the IAEA with access to the two suspect sites and facilitate verification activities.
Sept. 4, 2020: In a quarterly report, the IAEA said that Iran’s stockpile of low-enriched uranium reached 2,105 kilograms, or about 10 times more than the JCPOA limit. The stockpile had grown some 544 kilograms since the last quarterly report, released in June. Iran also began operating slightly more advanced centrifuges, but not enough shorten its breakout time, which remained three to four months. When Iran was in full compliance with the JCPOA, its breakout time had been 12 months.
In a separate safeguards report, the U.N. watchdog confirmed that it had visited one undeclared nuclear site to take environmental samples. The agency said it would visit another suspect site later in September.
Nov. 11, 2020: The IAEA reported that Iran’s stockpile of low-enriched uranium reached 2,443 kg (2.7 tons), or about 12 times more than the JCPOA limit. The stockpile had grown by 337.5 kg since the prior report released in September, a slower rate of growth than previously recorded. Iran installed 174 IR-2M centrifuges and conducted tests of three IR-4 advanced centrifuges.
The IAEA found Iran’s explanations for uranium particles detected at an undeclared nuclear site to be “unsatisfactory” and “not technically credible.”
Nov. 17, 2020: The IAEA reported that Iran began feeding uranium gas into 174 IR-2M advanced centrifuges at Natanz, the IAEA.
Dec. 4, 2020: Iran informed the IAEA that it would install three new cascades of advanced centrifuges. Each cascade was made up of more than 150 centrifuges.
Jan. 4, 2021: The IAEA confirmed that Iran had begun enriching uranium up to 20 percent at Fordo. The agency verified that centrifuges cascades at Fordo had been reconfigured to enrich levels of uranium from 4.1 percent to 20 percent.
Feb 2, 2021: The IAEA confirmed that Iran had completed installation of 174 more IR-2M centrifuges at Natanz and began feeding uranium gas into them. In total, Iran was enriching uranium with 5060 IR-1 centrifuges and 348 IR-2M centrifuges at Natanz.
Feb. 10, 2021: The IAEA confirmed that Iran had enriched 3.6 grams of natural uranium metal. Iran would need 500 grams of highly enriched uranium metal for a nuclear weapon core.
Feb. 15, 2021: Iran threatened to block IAEA snap inspections if the U.S. did not lift sanctions by February 21. "All these steps are reversible if the other party changes its path and honors its obligations,” Foreign Ministry spokesman Saeed Khatibzadeh said. The government specified that it would stop complying with the Additional Protocol -- a voluntary agreement that gives IAEA inspectors access to sites and facilities that support the country’s nuclear program but do not house nuclear materials. Iran ratified the Additional Protocol as part of the 2015 nuclear deal.
Feb. 17, 2021: Iran informed the IAEA that it would install two new cascades of advanced centrifuges at Natanz. Each cascade had 174 IR-2M centrifuges and would enrich uranium up to 5 percent.
Feb. 19, 2021: The IAEA detected uranium particles at two sites that may have been used for the storage and testing of undeclared nuclear materials in the early 2000s. Iran had previously blocked access to the sites for seven months before granting the IAEA access in August 2020, which called its commitment to transparency into question. Tehran had a secret nuclear weapons program until 2003, when it was disbanded, according to U.S. intelligence.
Feb. 21, 2021: The IAEA and Iran agreed on an compromise that would provide the nuclear watchdog less access to the country's declared and undeclared nuclear sites. Under the arrangement, the nuclear watchdog could not access cameras installed at declared nuclear sites but Iran will be required to save all surveillance footage for three months. If the United States lifts sanctions on Iran, Tehran will hand over the tapes to the IAEA. If the Biden administration does not lift punitive economic measures, the footage “will be deleted forever," the Atomic Energy Organization of Iran said. IAEA director general Rafael Grossi called it a “temporary solution” that “salvages the situation.”
Feb. 23, 2021: Iran suspended compliance with the Additional Protocol, a voluntary agreement that grants inspectors “snap” inspections and was part of the 2015 nuclear deal negotiated with the world’s six major powers. But Foreign Minister Mohammad Javad Zarif said that the step, and all other breaches of the deal, was "reversible" if the Biden administration lifted sanctions.
Mar. 1, 2021: Iran had failed to provide a "necessary, full and technically credible explanation" for the presence of uranium particles at undeclared sites, IAEA chief Rafael Grossi told the Board of Governors. "The Agency is deeply concerned that undeclared nuclear material may have been present at this undeclared location and that such nuclear material remains unreported by Iran under its Safeguards Agreement," he said.
Mar. 8, 2021: The IAEA confirmed that Iran had begun feeding uranium gas into a third cascade of advanced centrifuges at Natanz, Reuters reported. A fourth cascade of IR-2M centrifuges was installed but not enriching uranium, while installation of a fifth cascade was ongoing. Each cascade had 174 IR-2M centrifuges.
Mar. 15, 2021: The IAEA confirmed that Iran had begun enriching uranium at Natanz with IR-4 centrifuges. The IR-4 was the second type of advanced centrifuge, after the IR-2M, operating at the Natanz facility.
Apr. 1, 2021: The IAEA confirmed that Iran had begun enriching uranium with a fourth cascade of 174 IR-2M centrifuges. Iran was now using a total of 696 IR-2M centrifuges at Natanz.
April 7, 2021: Iran and the IAEA delayed talks in Tehran originally scheduled for early April. Rafael Grossi, director general of the International Atomic Energy Agency, told Newsweek that the agency planned to ask Iran questions about uranium participles discovered at undeclared sites.
April 8, 2021: Deputy Foreign Minister Abbas Araghchi met with IAEA Director General Grossi while in Vienna. Araghchi said that the IAEA would play an "important role" in verification if Iran came to an agreement with the world powers over returning to compliance with the JCPOA. He added that Iran would engage with the IAEA "in good faith" about outstanding nuclear issues, such as the discovery of uranium particles at undeclared sites. "I am confident we are able to resolve those questions as soon as possible," he told Press TV.
April 10, 2021: Iran began testing its most advanced nuclear centrifuge, the IR-9, at the Natanz enrichment site. Under the nuclear deal, Iran could only operate 5,060 first-generation IR-1 centrifuges until 2025. The IR-9 can enrich uranium 50 times faster than the IR-1.
April 11, 2021: An explosion at Natanz hit the power supply for centrifuges and caused damage that could take up to nine months to fully repair, The New York Times reported. It was the second major attack to sabotage operations at Natanz in less than a year. In July 2020, an explosion caused significant damage to a centrifuge factory. Foreign Minister Zarif blamed Israel and vowed revenge. “We will not fall into their trap,” he told a state television. “We will not allow this act of sabotage to affect the nuclear talks.”
April 13, 2021: Iran said that it will begin enriching uranium to 60 percent, the highest level of enrichment that it has publicly acknowledged. The move would be a major breach of the 2015 nuclear deal and brought Tehran closer to having weapons grade uranium. Iran also planned to install 1,000 additional centrifuges at Natanz. The White House said that it was “concerned” about the “provocative” announcement.
April 14, 2021: Britain, France and Germany expressed "grave concern" about Iran's decision to enrich uranium up to 60 percent. "Iran has no credible civilian need for enrichment at this level," the three European countries said in a joint statement. Secretary of State Antony Blinken called the decision to enrich up to 60 percent "provocative" and that it "calls into question Iran's seriousness" at the Vienna talks. "We're committed to pursuing that process, but the real question is whether Iran is," he said in Brussels. The IAEA said that Iran "had almost completed" preparations to enrich uranium up to 60 percent.
April 15, 2021: Indirect talks over getting the United State and Iran back into compliance with the JCPOA resumed in Vienna. In Tehran, President Rouhani reiterated that Iran was not seeking a nuclear weapon. “We can enrich 90 percent today, but we stand by our word and we are not looking for an atomic bomb,” he said during a cabinet meeting. “It is YOU who made and stockpiled the atomic bomb and are still making bombs. This is what YOU do. Do not accuse us of making bombs, Iran's activities are completely peaceful.”
April 16, 2021: Iran began enriching uranium up to 60 percent. “We are producing about nine grams of 60 percent enriched uranium an hour,” AEOI chief Salehi said. President Joe Biden said that the step was not "helpful" to negotiations in Vienna. "We are, though, nonetheless, pleased that Iran has continued to agree to engage in discussions, indirect discussions with us and with our partners on how we move forward," he said at a news conference in the Rose Garden.
April 19, 2021: The IAEA and the Iranian government began expert-level talks in Vienna over uranium particles discovered by the nuclear watchdog at undeclared sites in Iran. The talks were aimed at "clarifying outstanding safeguards issues," the IAEA said.
April 21, 2021: Iran installed more advanced centrifuges at the Natanz nuclear facility, the IAEA reported. Iran now had a total of 1,044 IR-2M centrifuges and 348 IR-4 centrifuges installed at Natanz.
April 22, 2021: The IAEA said that Iran was using fewer centrifuges to produce highly enriched uranium gas. Initially, Iran was using one cascade of IR-4 centrifuges and one cascade of IR-6 centrifuges to enrich uranium up to 60 percent. It converted the IR-4 centrifuges to instead enrich uranium up to 20 percent, the nuclear watchdog reported.
May 11, 2021: Iran has enriched uranium to 63 percent, the IAEA reported. The level of enrichment was "consistent with the fluctuations of the enrichment levels (described by Iran)," the agency told member states.
May 24, 2021: Iran and the IAEA extended a deal to retain surveillance footage at declared nuclear sites by one month. The agreement would expire on June 24, less than a week after Iran's presidential election on June 18. The extension was designed to give more time for negotiations in Vienna to bring Iran and the United States back into compliance with the 2015 nuclear deal. "I recommend that they use this opportunity, which has been provided in good faith by Iran, and lift all the sanctions in a practical and verifiable manner," Ambassador Kazem Gharibabadi, Iran's representative to the U.N. watchdog, said.
May 31, 2021: The IAEA said that Iran had failed to provide a "necessary explanation" for the presence of uranium particles at three undeclared sites previously inspected by the agency. "The lack of progress in clarifying the Agency's questions concerning the correctness and completeness of Iran's safeguards declarations seriously affects the ability of the Agency to provide assurance of the peaceful nature of Iran's nuclear program," the U.N. nuclear watchdog said in a report to member states. The IAEA estimated that Iran had 3,241 kilograms of enriched uranium, an increase of 273 kg since the last quarterly report. The estimate was the smallest increase in Iran's nuclear stockpile since August 2019.
June 7, 2021: Iran had made no "concrete progress" in explaining the presence of uranium particles at three undeclared sites, the head of the U.N.'s nuclear watchdog reported. Tehran's refusal to answer questions from inspectors "seriously affects the ability of the agency to provide assurance of the peaceful nature of Iran’s nuclear program,” Director General Rafael Grossi told the IAEA's board of governors. "The Iranian government has reiterated its will to engage and to cooperate and to provide answers, but they haven’t done that so far," he added.
June 15, 2021: Iran has produced 6.5 kg (14 lbs) of 60 percent enriched uranium, the government reported. The country also was on track to produce more uranium enriched to 20 percent than required by a law passed by Parliament in December. “The Atomic Energy Organization was supposed to produce 120 kg (265 lbs) of 20 percent enriched uranium in a year," spokesperson Ali Rabiei said. "According to the latest report, we now have produced 108 kg (238 lbs) of 20 percent uranium in the past five months."
Andrew Hanna, a program specialist at the U.S. Institute of Peace, assembled this report.