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1 [1] (March 27, 2025)

handle is hein.crs/irnadnrwe0001 and id is 1 raw text is: 





            Congressional Research Service
            lnforrning the legislative debate since 1914



Iran and Nuclear Weapons Production


Background
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. (For
additional information, see CRS Report RL34544, Iran 's
Nuclear Program: Status, by Paul K. Kerr.)
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 only
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. (For more information, see
CRS  Report R40094, Iran 's Nuclear Program: Tehran 's
Compliance  with International Obligations, by Paul K.
Kerr.)

Then-President Donald Trump announced  in May 2018 that
the United States was ending U.S. participation in the
JCPOA.  Over time, Iran subsequently 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. This program's goal, according to U.S. officials and the
IAEA,  was to develop an implosion-style nuclear weapon
for Iran's Shahab-3 ballistic missile. Tehran has not made a
decision to develop nuclear weapons, according
and 2025 public U.S. intelligence assessments.
U.S. Intelligence Community Annual Threat Assessment
published by the Office of the Director of National
Intelligence (ODNI) identifies Iran's Supreme Leader Ali
Khamenei  as the final decisionmaker over 
to develop nuclear weapons.


Updated March  27, 2025


The U.S. government assessed prior to the JCPOA that Iran
had not mastered all of the necessary technologies for
building a nuclear weapon. However, Tehran may now be
conducting work on such technologies. The 2024 U.S.
Intelligence Community Annual Threat Assessment)
observes that Iran is not currently undertaking the key
nuclear weapons-development activities necessary to
produce a testable nuclear device. But this phrase is absent
from 2024 and 2025 ODNI  assessments of Tehran's nuclear
program.
The JCPOA-mandated   restrictions on Iran's nuclear
program, as well as the agreement's 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 (see CRS Report R40094). More
recently, an ODNI spokesperson indicated that the U.S.
intelligence community is capable of detecting Iranian
efforts to build a nuclear weapon, the Wall Street Journal
reported on August 9, 2024.
Estimated Nuclear Weapons
Development Timelines
U.S. estimates concerning Iranian nuclear weapon
development account for the time necessary to produce a
sufficient amount of weapons-grade HEU and also
complete the remaining steps necessary for an implosion-
style nuclear device suitable for explosive testing.
Such a device, according to the Office of Technology
Assessment, uses a shell of chemical high-explosive
surrounding the nuclear material ... to rapidly and uniformly
compress the nuclear material to form a supercritical mass
necessary for a sustained nuclear chain reaction.


to  2024       Fissile Material Production
The 2025       The time needed to produce enough weapons-grade HEU
ssessment      for a nuclear weapon is a function of a nuclear program's
)nal           enrichment capacity, as well as the mass and u-235 content
               of the UF6 stockpile fed into the enrichment process. LEU
mny decision   used in nuclear power reactors typically contains less than
               5%  u-235; research reactor fuel can be made using enriched
               uranium containing 20% u-235; HEU  used in nuclear
               weapons  typically contains about 90% u-235.

ittps://Crsreports.congress.gov

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