Updated March 1, 2021
Iran’s Nuclear Program and U.N. Sanctions Reimposition
U.N. Security Council Resolution 2231 (2015), which the
enable the agency to detect the diversion of nuclear material
council adopted on July 20, 2015, implements the Joint
from declared nuclear facilities, as well as to detect
Comprehensive Plan of Action (JCPOA) and contains other
undeclared nuclear activities and material. (See CRS Report
provisions concerning Iran’s nuclear program, Tehran’s
R40094, Iran’s Nuclear Program: Tehran’s Compliance
development of missiles, and arms transfers to and from
with International Obligations, by Paul K. Kerr.)
Iran. In August 2020, the United States has invoked the
Iran is also implementing the Additional Protocol to its
resolution’s “snapback” mechanism, which requires the
comprehensive safeguards agreement. Such protocols
Security Council to reimpose U.N. sanctions lifted pursuant
increase the IAEA’s ability to investigate undeclared
to Resolution 2231 and the JCPOA.
nuclear facilities and activities in nonnuclear-weapon states
The JCPOA, finalized in July 2015 by Iran and China,
by increasing the agency’s authority to inspect certain
France, Germany, Russia, the United Kingdom, and the
nuclear-related facilities and demand information from
United States (collectively known as the P5+1), requires
member states. Pursuant to its JCPOA commitments, Iran is
Iran to implement constraints on its uranium enrichment
implementing provisionally its additional protocol; Tehran
and heavy water nuclear reactor programs, as well as allow
is to seek ratification of the protocol by the Iranian
the International Atomic Energy Agency (IAEA) to monitor
parliament no later than October 2023. Iran originally
Tehran’s compliance with the agreement. Prior to the
signed such an additional protocol in late 2003, but stopped
JCPOA, these programs caused international concern
implementing it in early 2006.
because they could both have produced fissile material for
The IAEA also continues to monitor JCPOA restrictions,
use in nuclear weapons.
which supplement Iran’s safeguards obligations and
Pursuant to the JCPOA, Tehran received relief from
prohibit Iran from engaging in a number of dual-use
sanctions imposed by the European Union, United Nations,
“activities which could contribute to the development of a
and United States. On the agreement’s January 16, 2016,
nuclear explosive device.” Should the JCPOA be
Implementation Day, the Security Council terminated
implemented as envisioned in the agreement, most of its
sanctions imposed by three previous resolutions on Iran; the
nuclear-related restrictions will expire. In that case,
council adopted the first of these resolutions (1996) in 2006
Tehran’s nuclear program will be governed indefinitely by
and the last (1929) in 2010. The sole operative Security
Iran’s obligations pursuant to the NPT, the government’s
Council resolution concerning Iran’s nuclear program,
IAEA comprehensive safeguards agreement and Additional
Resolution 2231, also stipulates that the council, which has
Protocol, and the dual-use restrictions described above.
been seized of the “Iranian nuclear issue” since 2006, is to
U.N. Security Council Resolution 2231
end its consideration of the matter in 2025. The resolution’s
(2015) and Snapback
snapback mechanism will then cease to be operational.
In addition to its JCPOA-related provisions, Resolution
In May 2018, President Donald Trump issued a
2231 imposes other requirements on Iran. For example, the
memorandum stating that the United States would no longer
resolution restricts exports of missile-rated items to Iran
participate in the JCPOA and would reimpose sanctions that
until October 2023; other restrictions concerning Iranian
had been suspended pursuant to the agreement. Arguing
imports and exports of conventional weapons expired on
that subsequent efforts by the remaining JCPOA
October 18, 2020. Despite lacking a direct connection to the
participants, known as the “P4+1,” were inadequate to
country’s nuclear program, previous arms restrictions, the
sustain the agreement’s benefits for Iran, the government
first of which were imposed by Security Council Resolution
has undertaken some nuclear activities that exceed JCPOA-
1747 (2007), were part of a broad U.S.-led approach of
mandated limits.
pressuring Iran to comply with relevant council resolutions.
Iran’s Nuclear Program and Selected
(For more on the arms restrictions, see CRS In Focus
JCPOA Provisions
IF11429, U.N. Ban on Iran Arms Transfers and Sanctions
Although some Iranian nuclear activities exceed JCPOA-
Snapback, by Kenneth Katzman.)
mandated limits, other aspects of the country’s nuclear
According to Resolution 2231, a JCPOA participant can,
program still comply with those limits. Tehran has
after notifying the Security Council of an issue that the
continued to allow IAEA monitoring of Iran’s JCPOA
government “believes constitutes significant non-
commitments, which supplement Tehran’s obligations
performance of [JCPOA] commitments,” trigger an
pursuant to its IAEA comprehensive safeguards agreement
automatic draft resolution keeping sanctions relief in effect.
and the nuclear Nonproliferation Treaty (NPT).
A U.S. veto of this resolution would both reimpose the
The NPT, which Iran ratified in 1970, includes prohibitions
suspended sanctions and end expiration of the conventional
on obtaining or producing nuclear weapons.
arms and missile-related export restrictions, as well as
Comprehensive safeguards agreements are designed to
Security Council consideration of the Iranian nuclear issue.
https://crsreports.congress.gov
Iran’s Nuclear Program and U.N. Sanctions Reimposition
Whether the United States has the status to invoke
Snapback would also end the process by which the Security
Resolution 2231’s snapback mechanism is under debate.
Council is to end in 2025 its consideration of the Iranian
The JCPOA lacks a withdrawal clause, and no Security
nuclear issue. The council adopted all of the resolutions that
Council resolution has altered the U.S. status as a JCPOA
imposed sanctions on Iran, as well as Resolution 2231,
“participant.” Resolution 2231 is silent on the mechanism’s
under Article 41 of Chapter VII, which enables the Security
status in the event that a P5+1 government ceases
Council to adopt “measures not involving the use of armed
implementing its JCPOA commitments. The United States
force,” including sanctions, “to give effect to its decisions”
neither describes itself nor acts as a JCPOA participant. Not
concerning “threats to the peace, breaches of the peace, and
only does the May 2018 memorandum mentioned above
acts of aggression.” Since adopting Resolution 1737 in
describe a U.S. decision to end its “participation” in the
2006, the council has been considering the Iranian nuclear
agreement, but the United States is also no longer
issue pursuant to Article 41. Iranian officials have touted
performing its JCPOA commitments.
the end of this status, which, as noted, Resolution 2231
Paragraph 10 of Resolution 2231 names the P5+1 countries
stipulates.
as “JCPOA participants.” But it is not clear that
Iranian statements and the JCPOA text indicate that the
“participants” is meant to include a P5+1 government that
government may stop performing all or some of its JCPOA
ceases performing its JCPOA commitments, or if the term
commitments if the Security Council extends the above-
merely identifies the JCPOA participants in July 2015.
mentioned arms restrictions or invokes snapback. If Iran
Notably, the agreement describes the P5+1 as “participants”
were to end its JCPOA participation entirely, the
when naming those states as members of the JCPOA-
government would be bound only by its comprehensive
established joint commission. The United States no longer
safeguards agreement, which is of indefinite duration. Iran
participates in that commission’s activities.
would not be bound by its Additional Protocol, should
In an August 20 letter to Security Council President
snapback occur before Iranian ratification of that
Indonesian Ambassador Dian Triansyah Djani, Secretary of
agreement.
State Michael Pompeo initiated the snapback process by
In such a scenario, the IAEA would retain its monitoring
notifying the council that Iran “is in significant non-
and inspection authority pursuant to Iran’s comprehensive
performance” of its JCPOA commitments. This action
safeguards agreement, but the scope of this authority would
followed the council’s rejection of a U.S.-sponsored draft
be narrower. For example, the agency would no longer be
resolution to extend Resolution 2231’s conventional arms-
able to monitor certain Iranian facilities that do not contain
related prohibitions. The letter argued that the Resolution
nuclear material but are associated with the government’s
2231 language cited above gives the United States the right
enrichment program. The IAEA would also retain its
to invoke snapback. The P4+1 Governments rejected this
authority to verify the absence of undeclared nuclear
claim. Moreover, Djani explained in an August 21 letter to
material and activities, but the agency would have fewer
the council that Pompeo’s letter “has no legal effect.” But
means to do so, if Iran’s additional protocol is not in force.
Pompeo stated on September 19 that “the snapback of
Moreover, Tehran would not be bound by any constraints
previously terminated UN sanctions…became effective”
on its enrichment program, which has been the main source
that same day.
of proliferation concern, although Iran would remain bound
UN Secretary General António Guterres wrote in a
by its NPT obligations. Significant expansion of Tehran’s
September 19 letter that the “majority” of Security Council
enrichment program would likely decrease the amount of
members have argued that Pompeo’s letter did not
time necessary for Iran to produce enough weapons-grade
constitute the notification necessary for snapback, The
highly enriched uranium for use in a nuclear weapon.
resulting uncertainty, he added, requires the Secretary to
Prior to the JCPOA, Iran was improving its ability to
refrain from proceeding on the matter. The Security
produce fissile material, despite U.N. and other sanctions’
Council could send the issue to the International Court of
evident success in slowing the nuclear program. At the
Justice for an advisory opinion, but the council lacks an
time, knowledgeable IAEA and U.S. officials observed that
independent mechanism to adjudicate these sorts of claims,
IAEA safeguards on Iran’s declared nuclear facilities would
and council members typically reach political settlements to
likely have detected an Iranian attempt to use them for
resolve such disputes. The implications of a council failure
producing nuclear weapons. (For more information, see
to reach such a settlement in this case are unclear.
CRS Report RL34544, Iran’s Nuclear Program: Status, by
On February 18, 2021, Acting U.S. Ambassador to the UN
Paul K. Kerr.) Nevertheless, Iran’s continuing nuclear
Richard Mills sent a letter to Security Council President UK
program concerned many governments. Indeed, U.S. and
Ambassador Barbara Woodward “reversing the previous
Israeli officials at the time planned for a possible attack on
administration’s position on the ... sanctions snapback
Iran’s nuclear program to prevent Tehran from developing a
issue,” a State Department official told reporters on
nuclear weapon. The end of Iranian JCPOA participation
February 18, adding that “the United States is affirming
could beget a similar situation.
that” Resolution 2231 “remains in full effect.”
Iranian officials have indicated that the government might
Possible Iranian Responses
withdraw from the NPT in response to snapback; the treaty
In addition to reimposing sanctions, snapback would
has a withdrawal provision. In this case, Tehran would not
remove other incentives for Iran to continue participating in
be bound by its comprehensive safeguards agreement or its
the agreement. These incentives include expiration of the
treaty obligations. Notably, these Iranian officials, echoing
restrictions on Iranian arms-related imports and exports, as
a long-standing government position, have stated that
well as missile-related imports described above.
Tehran would still refrain from producing nuclear weapons.
https://crsreports.congress.gov
Iran’s Nuclear Program and U.N. Sanctions Reimposition
IF11583
Paul K. Kerr, Specialist in Nonproliferation
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https://crsreports.congress.gov | IF11583 · VERSION 12 · UPDATED