The following is the July 25, 2022, Congressional Research Service In Focus report, Iran and Nuclear Weapons Production.
From the report
Iran’s nuclear program has generated widespread concern that Tehran is pursuing nuclear weapons. According to U.S. intelligence assessments, Tehran has the capacity to produce nuclear weapons at some point, but has halted its nuclear weapons program and has not mastered all of the necessary technologies for building such weapons.
Since the early 2000s, Tehran’s construction of gas centrifuge uranium enrichment facilities has been the main source of proliferation concern. Gas centrifuges enrich uranium by spinning uranium hexafluoride (UF6) gas at high speeds to increase the concentration of the uranium-235 (u-235) isotope. Such centrifuges can produce both low-enriched uranium (LEU), which can be used in nuclear power reactors, and highly enriched uranium (HEU), which is one of the two types of fissile material used in nuclear weapons. Tehran asserts that its enrichment program is meant to produce fuel for peaceful nuclear reactors.
The 2015 Joint Comprehensive Plan of Action (JCPOA) requires Iran to implement various restrictions on its nuclear program, as well as to accept specific monitoring and reporting requirements.
Then-President Donald Trump announced in May 2018 that the United States was ending U.S. participation in the JCPOA. Following this decision, Iran stopped implementing much of this agreement, as well as JCPOA-required International Atomic Energy Agency (IAEA) monitoring. Beginning in July 2019, the IAEA verified that some of Iran’s nuclear activities were exceeding JCPOA-mandated limits. Tehran’s subsequent expansion of the country’s enrichment program has decreased the amount of time needed for Iran to produce enough weapons-grade HEU for a nuclear weapon—an action frequently termed “breakout.”
According to official U.S. assessments, Iran halted its nuclear weapons program in late 2003 and has not resumed it. For example, the CIA has no evidence that Iranian Supreme Leader Ayatollah Ali Khamene’i “has made a decision to move to weaponize,” CIA Director William Burns said stated during a December 2021 Wall Street Journal interview. This program’s goal, according to U.S. officials, was to develop an implosion-style nuclear weapon for Iran’s Shahab-3 ballistic missile.
The U.S. government assessed prior to the JCPOA that Tehran had not mastered all of the necessary technologies for building a nuclear weapon. Apparently confirming persisting gaps in Iran’s nuclear weapons knowledge, the 2022 U.S. Intelligence Community Annual Threat Assessment observes that “Iran is not currently undertaking the key nuclear weapons-development activities … necessary to produce a nuclear device.” An April 2022 State Department report contains a similar conclusion.
The JCPOA-mandated restrictions on Iran’s nuclear program and Iran-specific monitoring and reporting requirements both supplement Tehran’s obligations pursuant to the government’s comprehensive IAEA safeguards agreement. Such agreements empower the agency to detect the diversion of nuclear material from peaceful purposes, as well as to detect undeclared nuclear activities and material. These agreements also require governments to declare their entire inventory of certain nuclear materials, as well as related facilities. Safeguards include agency inspections and monitoring of declared nuclear facilities.
Prior and subsequent to the JCPOA’s January 2016 implementation, IAEA and U.S. officials expressed confidence in the ability of both the IAEA and the U.S. intelligence community to detect an Iranian breakout attempt using either Tehran’s IAEA-monitored facilities or clandestine facilities.
Download the report here.