Iran Watch Newsletter: April 2021

April 30, 2021

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  • Newsletters

This month’s newsletter features an update to a report estimating Iran’s ability to make a dash to produce fuel for a small nuclear arsenal and a table describing Iran’s potentially nuclear-capable missiles, which also pose a growing conventional threat to military bases and civilian infrastructure in the Middle East and beyond. The table highlights the payload, range, precision, and operational status of key missiles.

The newsletter also features profiles of entities linked to Iran’s past and potentially ongoing nuclear weapons research, and news about Iran’s reaction to an explosion and blackout at its Natanz uranium enrichment plant. Other items include documents from the Iran Watch library on negotiations to revive the Joint Comprehensive Plan of Action (JCPOA) and international responses to Iran’s recent decision to enrich uranium up to 60% purity.

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Report Update | Iran’s Nuclear Timetable: The Weapon Potential

Despite an expansion in its declared uranium enrichment capacity, Iran still cannot make a sudden dash to produce the fuel for a small nuclear arsenal of five implosion-type warheads – the goal Iran set for itself when it began to work on nuclear weapons decades ago. Instead, the main nuclear weapon risk continues to come from secret sites, which Iran has used for illicit work in the past. That risk will increase as Iran develops more powerful centrifuges, allowing sites to be smaller and easier to hide. Perfecting such centrifuges is a vital step in the long nuclear game Iran has been playing for decades.

This update relies on data from the latest public report by the International Atomic Energy Agency (IAEA). It does not reflect any damage done to centrifuges following an attack at the Natanz enrichment plant on April 11. (Image courtesy of Tasnim News Agency.)

Read the updated report here.


Background Report | Table of Iran’s Missile Arsenal

Iran’s missile arsenal is the largest in the Middle East. Despite concerns voiced by the international community, Tehran has persisted in developing a wide array of ballistic and cruise missiles that are either inherently or potentially capable of carrying a nuclear warhead, as well as space launch vehicles that use many of the same technologies as intercontinental ballistic missiles (ICBMs). Over the past decade, Iran has also improved the precision, accuracy, and survivability of its missiles, making them an increasingly potent conventional threat to military bases and civilian infrastructure in the Middle East and beyond.

View the table of Iran’s known and estimated missile capabilities, including range and payload, here.



The United States has sanctioned multiple Iranian entities involved in research related to nuclear weapons development, including a defense research institute led until November 2020 by the late Mohsen Fakhrizadeh-Mahabadi, a U.N.-sanctioned nuclear scientist.

Organization of Defensive Innovation and Research (SPND)

A research institute “primarily responsible for research in the field of nuclear weapons development,” according to the U.S. Department of State; sanctioned by the United States in 2014; associated with “possible military dimensions to Iran’s nuclear program,” according to the International Atomic Energy Agency (IAEA).

Kimiya Pakhsh Shargh

An SPND subsidiary sanctioned by the United States in 2019; procures materials from foreign suppliers, including radioisotopes; reportedly produces research, laboratory, and medical equipment.

Paradise Medical Pioneers Company

An SPND front company sanctioned by the United States in 2019; personnel have included Fakhrizadeh and other senior SPND officials; involved in research and production of composites, steels, polymers, and other materials for the SPND and other customers.



Blackout Hits Iran Nuclear Site in What Appears to Be Israeli Sabotage | The New York Times

April 11: Iran’s Natanz nuclear facility suffered a power outage that Ali Akbar Salehi, the head of the Atomic Energy Organization of Iran (AEOI), described as “nuclear terrorism” on April 11. Unnamed Israeli and U.S. intelligence officials said that an Israeli-orchestrated explosion had destroyed an internal power system feeding electricity to underground centrifuges at Natanz. The officials said that Iran could need at least nine months to return Natanz’s enriched uranium production to previous levels. Behrouz Kamalvandi, an AEOI spokesman, reported that the entire complex had lost power but claimed that there were no casualties or damage. Israel neither confirmed nor denied responsibility for the action.

Iran Starts Enriching Uranium to 60%, Its Highest Level Ever | Associated Press

April 16: Mohammad Bagher Qalibaf, speaker of the Iranian Parliament, announced on April 16 that Iran had begun enriching uranium gas to 60 percent purity. Ali Akbar Salehi, head of the Atomic Energy Organization of Iran (AEOI), specified that Iranian centrifuges were producing nine grams of uranium enriched to 60 percent per hour but that this amount would decrease to five grams per hour in the near future. Earlier in the week, inspectors from the International Atomic Energy Agency (IAEA) visited the Natanz nuclear facility and said that Iran’s planned 60-percent enrichment would take place at the aboveground portion of the site. Iranian officials and state media cast the move to 60-percent enrichment as a response to the previous week’s sabotage at Natanz, which damaged centrifuges there. Before then, Iran had been enriching uranium to 20 percent. The Joint Comprehensive Plan of Action (JCPOA), the 2015 international agreement placing limits on Iran’s nuclear program, prohibits Iran from enriching uranium to more than 3.67 percent. The European Union, France, Germany, and the United Kingdom expressed concern at the Iranian decision.

Iran Adds Machines at Enrichment Plant Struck by Blast—IAEA | Reuters

April 21: The International Atomic Energy Agency (IAEA) reported on April 21 that Iran had installed six cascades of “up to” 1,044 IR-2m centrifuges and two cascades of “up to” 348 IR-4 centrifuges at the underground portion of the Natanz nuclear site. The IAEA did not specify how many of the newly installed centrifuges Iran was using to enrich uranium. Iran also informed the IAEA that it plans to install four additional cascades of IR-4 centrifuges in the underground facility, where an explosion and power outage earlier in the month damaged an unknown number of centrifuges. The Joint Comprehensive Plan of Action (JCPOA), the 2015 international agreement restricting Iran's nuclear program, limits the country to the use of less efficient IR-1 centrifuges at the underground portion of Natanz.



For much of April, the remaining parties to the JCPOA held a series of meetings to facilitate a return to compliance with the accord by Iran and the United States.

Even as the Biden administration seeks to rejoin the JCPOA, the United States and its allies continue to scrutinize Iran’s nuclear program and other activities.

In mid-April, a damaging blackout struck Iran’s Natanz nuclear facility, the second case of suspected Israeli sabotage at the site in less than one year. In the aftermath of the incident, Iran began enriching small quantities of uranium to 60 percent purity.