UNITED NATIONS — After four weeks of tense negotiations among 191 global signatories, the latest United Nations review conference for the landmark Nuclear Nonproliferation Treaty (NPT) concluded on Friday with no consensus on a final outcome, derailed by sharp open confrontation between the United States and Iran over Tehran’s contested nuclear program.
Do Hung Viet, Vietnam’s U.N. Ambassador and the chair of the 2025 review conference, confirmed that participating states could not reach agreement even on a heavily compromised, watered-down closing document. While he declined to name which delegation or group of delegations blocked consensus, the entire conference was overshadowed by escalating tensions between Washington and Tehran that intensified ahead of the U.S.-Israeli military campaign against Iran that launched in late February.
This outcome marks the third consecutive failure for a major NPT review conference, a discouraging milestone for the global pact that has stood for more than five decades as the foundational framework for international nuclear nonproliferation and disarmament efforts. The 2022 NPT review also ended without agreement, after Russia blocked consensus over language condemning its invasion of Ukraine and its illegal occupation of Europe’s largest nuclear facility, the Zaporizhzhia Nuclear Power Plant.
Clashes between U.S. and Iranian delegates dominated the conference from its opening session on April 27. The U.S. opened with sharp accusations that Iran has openly violated its NPT commitments, escalating those attacks in closing remarks that labeled Tehran a “prolific treaty violator” that spent the conference evading accountability for “grotesque violations” of its obligations. U.S. officials point to Iran’s previous enrichment of uranium to near weapons-grade purity, as well as its refusal to grant inspection access to nuclear sites damaged in U.S. airstrikes last June, as evidence of its noncompliance. Under the NPT, all signatory nations are required to grant full, unrestricted access to International Atomic Energy Agency inspectors to verify civilian nuclear activities.
Iran has pushed back aggressively against these claims, rejecting U.S. assertions that it is pursuing a nuclear weapons program and maintaining that all its nuclear activities are strictly for peaceful civilian purposes, including energy production and medical research. Iranian delegates countered that the U.S. and Israel’s repeated airstrikes on Iranian nuclear facilities themselves represent clear violations of international law, and accused the U.S. of leading a “relentless campaign” to frame Iran’s defensive actions and legitimize Washington’s own unlawful military attacks on the country.
The failure to reach agreement has sparked deep concern among arms control experts, who warn that the deadlock signals growing erosion of the global nonproliferation framework. Daryl Kimball, executive director of the Washington-based Arms Control Association, noted that while many nations continue to express rhetorical support for the NPT, the landmark agreement’s foundational pillars are weakening due to persistent inaction, disengagement, and intransigence from major global powers.
“Much more enlightened, engaged, and pragmatic leadership and diplomacy will be needed to guard against the growing risks of an unconstrained nuclear buildup, threats to resume nuclear testing, and the risk of a nuclear-armed Iran,” Kimball said.
Rebecca Johnson, founding executive director of the U.K.-based Acronym Institute for Disarmament Diplomacy, extended criticism to the world’s two largest nuclear arsenals, the U.S. and Russia, arguing that both major powers have consistently refused to uphold their own NPT disarmament commitments. She charged that the two nuclear superpowers continue to double down on explicit nuclear threats, shift blame to other nations, and actively undermine or ignore the disarmament obligations they agreed to under the treaty and related global pacts.