Updated August 17, 2020
Iran’s Nuclear Program and U.N. Sanctions Reimposition
U.N. Security Council Resolution 2231 (2015), which the
The NPT, which Iran ratified in 1970, includes prohibitions
council adopted on July 20, 2015, implements the Joint
on obtaining or producing nuclear weapons.
Comprehensive Plan of Action (JCPOA) and contains other
Comprehensive safeguards agreements are designed to
provisions concerning Iran’s nuclear program, Tehran’s
enable the agency to detect the diversion of nuclear material
development of missiles, and arms transfers to and from
from declared nuclear facilities, as well as to detect
Iran. The United States has threatened to invoke the
undeclared nuclear activities and material. (See CRS Report
resolution’s “snapback” mechanism, which requires the
R40094, Iran’s Nuclear Program: Tehran’s Compliance
Security Council to reimpose U.N. sanctions lifted pursuant
with International Obligations, by Paul K. Kerr.)
to Resolution 2231 and the JCPOA.
Iran is also implementing the Additional Protocol to its
The JCPOA, finalized in July 2015 by Iran and China,
comprehensive safeguards agreement. Such protocols
France, Germany, Russia, the United Kingdom, and the
increase the IAEA’s ability to investigate undeclared
United States (collectively known as the P5+1), requires
nuclear facilities and activities in nonnuclear-weapon states
Iran to implement constraints on its uranium enrichment
by increasing the agency’s authority to inspect certain
and heavy water nuclear reactor programs, as well as allow
nuclear-related facilities and demand information from
the International Atomic Energy Agency (IAEA) to monitor
member states. Pursuant to its JCPOA commitments, Iran is
Tehran’s compliance with the agreement. Prior to the
implementing provisionally its additional protocol; Tehran
JCPOA, these programs caused international concern
is to seek ratification of the protocol by the Iranian
because they could both have produced fissile material for
parliament no later than October 2023. Iran originally
use in nuclear weapons.
signed such an additional protocol in late 2003, but stopped
implementing it in early 2006.
Pursuant to the JCPOA, Tehran received relief from
sanctions imposed by the European Union, United Nations,
The IAEA also continues to monitor JCPOA restrictions,
and United States. On the agreement’s January 16, 2016,
which supplement Iran’s safeguards obligations and
Implementation Day, the Security Council terminated
prohibit Iran from engaging in a number of dual-use
sanctions imposed by three previous resolutions on Iran; the
“activities which could contribute to the development of a
council adopted the first of these resolutions (1996) in 2006
nuclear explosive device.” Should the JCPOA be
and the last (1929) in 2010. The sole operative Security
implemented as envisioned in the agreement, most of its
Council resolution concerning Iran’s nuclear program,
nuclear-related restrictions will expire. In that case,
Resolution 2231, also stipulates that the council, which has
Tehran’s nuclear program will be governed indefinitely by
been seized of the “Iranian nuclear issue” since 2006, is to
Iran’s obligations pursuant to the NPT, the government’s
end its consideration of the matter in 2025.
IAEA comprehensive safeguards agreement and Additional
Protocol, and the dual-use restrictions described above.
In May 2018, President Donald Trump issued a
memorandum stating that the United States would no longer
U.N. Security Council Resolution 2231
participate in the JCPOA and would reimpose sanctions that
(2015) and Snapback
had been suspended pursuant to the agreement. Arguing
In addition to its JCPOA-related provisions, Resolution
that subsequent efforts by the remaining JCPOA
2231 imposes other requirements on Iran. For example, the
participants, known as the “P4+1,” were inadequate to
sustain the agreement’s benefits for Iran, the government
resolution prohibits certain arms transfers to Iran; bans all
Iranian exports of conventional arms until October 18,
has undertaken some nuclear activities that exceed JCPOA-
2020; and restricts exports of missile-rated items to Iran
mandated limits. Iranian officials continue to assert that
until October 2023. Despite lacking a direct connection to
Tehran will resume implementing all of its JCPOA
the country’s nuclear program, previous arms restrictions,
commitments if the P4+1 does so.
the first of which were imposed by Security Council
Iran’s Nuclear Program and Selected
Resolution 1747 (2007), were part of a broad U.S.-led
JCPOA Provisions
approach of pressuring Iran to comply with relevant council
resolutions. (For more on the arms restrictions, see CRS In
Although some Iranian nuclear activities exceed JCPOA-
Focus IF11429, U.N. Ban on Iran Arms Transfers, by
mandated limits, other aspects of the country’s nuclear
Kenneth Katzman.)
program still comply with those limits. Tehran has
continued to allow IAEA monitoring of Iran’s JCPOA
According to Resolution 2231, a JCPOA participant can,
commitments, which supplement Tehran’s obligations
after notifying the Security Council of an issue that the
pursuant to its IAEA comprehensive safeguards agreement
government “believes constitutes significant non-
and the nuclear Nonproliferation Treaty (NPT).
performance of [JCPOA] commitments,” trigger an
automatic draft resolution keeping sanctions relief in effect.
A U.S. veto of this resolution would both reimpose the
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Iran’s Nuclear Program and U.N. Sanctions Reimposition
suspended sanctions and end expiration of the conventional
acts of aggression.” Since adopting Resolution 1737 in
arms and missile-related export restrictions, as well as
2006, the council has been considering the Iranian nuclear
Security Council consideration of the Iranian nuclear issue.
issue pursuant to Article 41. Iranian officials have touted
the end of this status, which, as noted, Resolution 2231
Whether the United States has the status to invoke
stipulates.
Resolution 2231’s snapback mechanism is under debate.
The JCPOA lacks a withdrawal clause, and no Security
Iranian statements and the JCPOA text indicate that the
Council resolution has altered the U.S. status as a JCPOA
government may stop performing all or some of its JCPOA
“participant.” Resolution 2231 is silent on the mechanism’s
commitments if the Security Council extends the above-
status in the event that a P5+1 government ceases
mentioned arms restrictions or invokes snapback. If Iran
implementing its JCPOA commitments. The United States
were to end its JCPOA participation entirely, the
neither describes itself nor acts as a JCPOA participant. Not
government would be bound only by its comprehensive
only does the May 2018 memorandum mentioned above
safeguards agreement, which is of indefinite duration. Iran
describe a U.S. decision to end its “participation” in the
would not be bound by its Additional Protocol, should
agreement, but the United States is also no longer
snapback occur before Iranian ratification of that
performing its JCPOA commitments.
agreement.
Paragraph 10 of Resolution 2231 names the P5+1 countries
In such a scenario, the IAEA would retain its monitoring
as “JCPOA participants.” But it is not clear that
and inspection authority pursuant to Iran’s comprehensive
“participants” is meant to include a P5+1 government that
safeguards agreement, but the scope of this authority would
ceases performing its JCPOA commitments, or if the term
be narrower. For example, the agency would no longer be
merely identifies the JCPOA participants in July 2015.
able to monitor certain Iranian facilities that do not contain
Notably, the agreement describes the P5+1 as “participants”
nuclear material but are associated with the government’s
when naming those states as members of the JCPOA-
enrichment program. The IAEA would also retain its
established joint commission. The United States no longer
authority to verify the absence of undeclared nuclear
participates in that commission’s activities.
material and activities, but the agency would have fewer
means to do so, if Iran’s additional protocol is not in force.
Arguing that the Resolution 2231 language cited above
gives the United States the right to invoke snapback, Trump
Moreover, Tehran would not be bound by any constraints
Administration officials threatened to take such a step if the
on its enrichment program, which has been the main source
Security Council were to reject a U.S.-sponsored draft
of proliferation concern, although Iran would remain bound
resolution to extend Resolution 2231’s conventional arms-
by its NPT obligations. Significant expansion of Tehran’s
related prohibitions. The council announced on August 14
enrichment program would likely decrease the amount of
that it had failed to adopt such a resolution. On the same
time necessary for Iran to produce enough weapons-grade
day, U.S. Ambassador Kelly Craft reiterated that the United
highly enriched uranium for use in a nuclear weapon.
States “has every right to initiate snapback” and added that
“the United States will follow through on that promise to
Prior to the JCPOA, Iran was improving its ability to
stop at nothing to extend the arms embargo.”
produce fissile material, despite U.N. and other sanctions’

evident success in slowing the nuclear program. At the
Officials from China and Russia, as well as the European
time, knowledgeable IAEA and U.S. officials observed that
Union, contest Washington’s claim regarding the U.S.
IAEA safeguards on Iran’s declared nuclear facilities would
JCPOA participant status. The Security Council could send
likely have detected an Iranian attempt to use them for
the issue to the International Court of Justice for an
producing nuclear weapons. (For more information, see
advisory opinion, but the council lacks an independent
CRS Report RL34544, Iran’s Nuclear Program: Status, by
mechanism to adjudicate these sorts of claims, and council
Paul K. Kerr.) Nevertheless, Iran’s continuing nuclear
members typically reach political settlements to resolve
program concerned many governments. Indeed, U.S. and
such disputes. The implications of a council failure to reach
Israeli officials at the time planned for a possible attack on
such a settlement in this case are unclear.
Iran’s nuclear program to prevent Tehran from developing a
nuclear weapon. The end of Iranian JCPOA participation
Possible Iranian Responses
could beget a similar situation.
In addition to reimposing sanctions, snapback would
Iranian officials have also indicated that the government
remove other incentives for Iran to continue participating in
might withdraw from the NPT in response to snapback; the
the agreement. These incentives include expiration of the
treaty contains a withdrawal provision. In this case, Tehran
restrictions on Iranian arms-related imports and exports, as
would not be bound either by its comprehensive safeguards
well as missile-related imports described above.
agreement or by its treaty obligations. Notably, these
Snapback would also end the process by which the Security
Iranian officials, echoing a longstanding government
Council is to end in 2025 its consideration of the Iranian
position, have stated that Tehran would still refrain from
nuclear issue. The council adopted all of the resolutions that
producing nuclear weapons.
imposed sanctions on Iran, as well as Resolution 2231,
under Article 41 of Chapter VII, which enables the Security
Paul K. Kerr, Specialist in Nonproliferation
Council to adopt “measures not involving the use of armed
IF11583
force,” including sanctions, “to give effect to its decisions”
concerning “threats to the peace, breaches of the peace, and


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Iran’s Nuclear Program and U.N. Sanctions Reimposition


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https://crsreports.congress.gov | IF11583 · VERSION 2 · UPDATED

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