Explainer: Why UN sanctions returned to Iran and what led up to them
The three European powers cited Tehran’s continued nuclear escalation and refusal to cooperate fully with international inspectors as justification
The United Nations has reimposed comprehensive economic and military sanctions on Iran after Britain, France, and Germany triggered the "snapback" mechanism on Aug. 28, 2025.
The three European powers cited Tehran's continued nuclear escalation and refusal to cooperate fully with international inspectors as justification.
Iran has strongly rejected the move, calling it "illegal and unjustified." Foreign Minister Abbas Araghchi declared that cooperation with the International Atomic Energy Agency (IAEA) was "no longer relevant," arguing that the E3 has diminished their role in negotiations. Before Brexit, the term was used to refer to the grouping of France, Germany, and the United Kingdom, especially during the negotiations with Iran from 2003.
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Tehran has warned that it will respond in a "proportionate and appropriate" manner, with some lawmakers threatening withdrawal from the Nuclear Non-Proliferation Treaty (NPT) and potential missile retaliation against Europe and the United States.
President Masoud Pezeshkian emphasized that while Iran remains committed to the NPT, the reinstatement of sanctions jeopardizes ongoing diplomatic efforts.
Origins of sanctions
1979: Hostage crisis
Sanctions against Iran began in November 1979 after radical students seized the US embassy in Tehran, taking American diplomats hostage. In response, the US froze approximately $12 billion in Iranian assets, banned imports, and imposed a trade embargo. These initial sanctions were lifted in January 1981 following the hostages' release under the Algiers Accords.
1980s–1990s: Terrorism and proliferation concerns
The United States designated Iran a state sponsor of terrorism in 1984, citing repeated support for international terrorism, which brought wide-ranging US sanctions. In the 1990s, legislation such as the Iran-Iraq Arms Nonproliferation Act (1992) and the Iran-Libya Sanctions Act targeted Iran's acquisition of weapons of mass destruction and restricted investments in sectors that could support such programs.
2000s: Nuclear program and UN sanctions
Global attention turned to Iran's nuclear program after uranium enrichment activities became public in 2002. The UN Security Council adopted multiple resolutions starting in 2006, including Resolution 1737, demanding that Iran suspend enrichment and imposing sanctions targeting nuclear-related goods, financial transactions, and arms. The UN cited Tehran's refusal to halt enrichment and allow inspections as justification for these measures.
2015–2018: The JCPOA period
The Joint Comprehensive Plan of Action (JCPOA), signed on July 14, 2015, by Iran and the P5+1 (the United States, United Kingdom, France, Russia, China, and Germany), significantly eased sanctions.
Under the agreement:
Iran agreed to limit enrichment, reduce nuclear stockpiles, and allow comprehensive inspections by the IAEA. In return, the UN suspended sanctions under Resolution 2231 (2015), while the US and EU lifted many nuclear-related restrictions.
Iran regained access to an estimated $29 billion in previously frozen funds, resumed oil exports, and reentered the global financial system via mechanisms like SWIFT.
Implementation Day, January 16, 2016, marked verification by the IAEA that Iran had met its commitments, temporarily restoring diplomatic and economic normalcy. However, many primary US sanctions, particularly those unrelated to nuclear issues, remained in effect.
Post-JCPOA developments and US withdrawal
The JCPOA's stability proved temporary. On May 8, 2018, US President Donald Trump announced the United States' withdrawal, describing the agreement as flawed. Washington reinstated and later expanded sanctions targeting Iran's financial sector, energy exports, and other economic areas. These measures were designed to pressure Iran to curb support for militant groups, halt ballistic missile development, and change regional behavior.
Following the US withdrawal, Iran gradually resumed enrichment above JCPOA limits and reduced transparency to inspectors. European partners attempted to preserve the deal but were unable to fully offset US sanctions.
2025: Snapback activation by the E3
On Aug. 28, 2025, the UK, France, and Germany triggered the UN snapback mechanism, reimposing comprehensive sanctions. The E3 cited multiple violations, including:
- Accumulating highly enriched uranium without civilian justification.
- Limiting cooperation with IAEA inspectors.
- Escalation of nuclear activity following regional attacks on Iranian facilities in June 2025.
The snapback effectively reinstates restrictions on arms transfers, banking, and international trade, aiming to compel Tehran back into compliance.
Iran's response
Iran has condemned the snapback sanctions and taken several countermeasures:
- Suspension of nuclear cooperation: Tehran declared IAEA engagement "no longer relevant."
- Diplomatic warnings: Officials threatened withdrawal from the NPT if sanctions persist.
- Military rhetoric: Lawmakers highlighted missile capabilities targeting Europe and select US cities.
- Financial caution: Despite tough rhetoric, reports indicate concern among senior officials over the economic impact of sanctions.
- Conditions for negotiation: President Pezeshkian demanded assurances against attacks on Iran's nuclear facilities to resume enrichment talks.
The reimposition of UN sanctions isolates Iran economically and diplomatically, potentially reducing its access to global banking, international trade, and military technology. Analysts say this could pressure Tehran to resume negotiations over its nuclear program but also risks further escalation if Iran retaliates.
Financially, the sanctions could hinder Iran's oil exports and access to frozen assets, affecting both domestic economic stability and global energy markets. Politically, the move may complicate relationships between Tehran and European powers, while also influencing the broader security dynamics in the Middle East. Observers note that the effectiveness of the sanctions will depend on the coordination among UN member states and Iran's willingness to reengage diplomatically.
