The US–Israel conflict with Iran and enduring inconsistencies in nuclear-sharing practices are exposing structural limits of the NPT regime, weakening its credibility and reshaping incentives around nuclear deterrence
The United States and Israel’s opposition to Iran’s nuclear programme has been a longstanding feature of West Asian geopolitics. However, the launch of Operation Epic Fury on 28 February 2026 marks a significant inflexion point. By shifting to full-scale military deterrence—including strikes against Iranian leadership, attacks on nuclear facilities at Natanz, Fordow, and Esfahan, and blockade of the Strait of Hormuz—the United States (US) has moved beyond the framework of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), diplomatic engagement. This also marks a departure from the traditional ‘snapback’ sanctions mechanism under the Joint Comprehensive Plan of Action (i.e. the ‘Iran nuclear deal’). With the US on the back foot in the still ongoing conflict, the collapse of Pakistan-mediated diplomatic talks, and Iran’s continued advancement of its nuclear programme, global nuclear governance appears to have reached a critical juncture.
Currently, 191 states are parties to the NPT, including the original five nuclear powers—the Permanent Five (P5) members of the United Nations Security Council: the US, Russia, the United Kingdom (UK), France, and China.
This war involves three distinct parties: the US (a nuclear power and a party to the NPT), Israel (the only nuclear power in the Middle East and which is not a signatory to the NPT), and Iran (a non-nuclear power that remains a signatory to the NPT and is barred from developing a nuclear arsenal). Currently, 191 states are parties to the NPT, including the original five nuclear powers—the Permanent Five (P5) members of the United Nations Security Council: the US, Russia, the United Kingdom (UK), France, and China. North Korea left the treaty in 2003. Israel, India, and Pakistan have, as nuclear powers, always remained outside it. This war is unusual in that it marks the first time a party to the NPT is using ‘disarmament by force’ against another party to the treaty. With the 11th Review Conference on the NPT (RevCon) at the United Nations, which commenced on 27 April 2026, the stakes could hardly be higher. This is especially so as the previous two RevCons in 2015 and 2022 failed to produce a consensus-based outcome document on the pathway to international nuclear non-proliferation. Further compounding these pressures is the expiration of the New Strategic Arms Reduction Treaty (New START) between the United States and Russia in February 2026, marking the end of the last legally binding limit on deployed nuclear warheads between the world’s two largest nuclear powers.
As the cornerstone of international nuclear non-proliferation, the NPT codified the 1967 status quo by recognising only the P5 as nuclear-weapon states. Under Articles I and II of the treaty, the P5 are prohibited from transferring (directly or indirectly) their nuclear weapons or assisting others in acquiring them; non-nuclear signatories are barred from developing nuclear capabilities. Article III further subjects non-nuclear signatories to safeguards and inspections by the International Atomic Energy Agency (IAEA) to ensure that their nuclear programmes remain exclusively for peaceful purposes. This position is, however, undermined by nuclear-sharing arrangements, including those between the US and NATO allies, and Russia and Belarus, which other NPT states have opposed as contravening the provisions of Articles I and II. The NATO arrangement predates the NPT—a line of defence taken by NATO members to claim the NPT’s non-retroactivity, in line with Article 28 of the Vienna Convention on the Law of Treaties (i.e. unless a different intention appears, a new treaty does not bind the parties in relation to anything predating the treaty that ceased to exist before the treaty entered into force). Opponents, however, argue that because planning, deployment, and training under these arrangements have continued after the NPT entered into force, they are not grandfathered under the treaty.
As the cornerstone of international nuclear non-proliferation, the NPT codified the 1967 status quo by recognising only the P5 as nuclear-weapon states.
Further, the claim that such nuclear-sharing arrangements do not constitute a transfer under Article I of the NPT is also open to rebuttal. This rests on the argument that the weapons remain under US custody and control in peacetime, and that any conditional transfer would occur only in wartime under NATO terms, during which the NPT is said to be effectively suspended. As the International Law Commission has clarified, armed conflicts do not ipso facto terminate or suspend treaties, particularly in the case of a multilateral treaty such as the NPT, which governs a critical global subject matter. China has also argued that US deployment and training under these arrangements constitute a special form of proliferation and effectively amount to a transfer, thereby violating Article I of the NPT. The argument of acquiescence is likewise contestable, as the extent to which NPT signatories were aware of NATO’s nuclear sharing arrangements at the time of signing cannot be definitively established from the NPT’s travaux préparatoires (preparatory works). Subsequent objections raised at Review Conferences by several Global South states—including Brazil, South Africa, Egypt, and Iran—further weaken this claim. The Russia–Belarus arrangement in 2023, which is more recent, has similarly involved the deployment of nuclear weapons in Belarus alongside Russian training for their use. France has also advanced its dissuasion avancée nuclear deterrence policy this year, intended to give France’s European allies a stake in shared nuclear deterrence under French command and control—functioning as a complement to, but also a strategic hedge against, the US nuclear umbrella. Taken together, the contentious nature of nuclear sharing arrangements creates legal jeopardy for the nuclear states under Article I and non-nuclear host states under Article II, which prohibits nuclear armament. It also weakens the credibility of opposition to other states pursuing nuclear armament.
In addition to the NPT, the non-nuclear states separately continue to pursue the goal of complete nuclear disarmament under the 2017 Treaty on the Prohibition of Nuclear Weapons, which lacks participation from the nine nuclear powers, rendering it a redundant effort. Simultaneously, the 1996 Comprehensive Nuclear-Test-Ban Treaty remains in limbo, especially with Russia’s 2023 revocation of its ratification without the US’s reciprocal ratification. Since last year, especially, there have been indications that Russia, China and the US might resume nuclear testing. The last known nuclear test among them was conducted by China in 1996. North Korea is the only country confirmed to have conducted nuclear tests in this century. Further, minilaterals like AUKUS normalise the transfer of nuclear technology outside traditional safeguards.
The contentious nature of nuclear sharing arrangements creates legal jeopardy for the nuclear states under Article I and non-nuclear host states under Article II, which prohibits nuclear armament. It also weakens the credibility of opposition to other states pursuing nuclear armament.
In its landmark 1996 advisory opinion, sought by the UN, the International Court of Justice held that neither the NPT nor customary international law contains a universal prohibition on the threat or use of nuclear weapons. The Court reached a non liquet, concluding that it could not definitively determine the lawfulness of the use of nuclear weapons—given their peculiar nature—even in an extreme act of self-defence. However, the Court unanimously affirmed that Article VI of the NPT creates a legal obligation for all signatories to pursue and conclude negotiations in good faith towards complete nuclear disarmament—one of the treaty’s core objectives. Nuclear-sharing arrangements are contentious in this regard, and the 2026 suspension of the New START Treaty signals a clear retreat from Article VI, particularly in the absence of clarity on the future course of action. This concern is further amplified by the ongoing US–Iran war. Following the June 2025 attacks on its nuclear sites and the Operation Epic Fury strikes in recent months, Iran is seriously considering withdrawal from the NPT. Such a move would remove IAEA oversight and could accelerate Iran’s path towards nuclear armament. The international system has, in effect, returned to a state of permanent nuclear readiness.
As per Stockholm International Peace Research Institute (SIPRI)’s latest data (January 2025), the nine nuclear-armed states together possess approximately 12,241 nuclear weapons, of which 9,614 are operational. The United States and Russia account for nearly 90 percent of deployed warheads and have extensive programmes underway to modernise and replace them. The increase in new warheads globally is expected to outpace the dismantling of retired ones. China’s arsenal has also expanded from 500 to 600 warheads—a primary reason cited by the United States for withdrawing from bilateral limits under the New START Treaty.
Whether more countries pursue an independent nuclear path or nuclear-sharing arrangements as the way forward, the risk is of a diffuse nuclear arms race. This makes the ongoing 11th RevCon perhaps the most critical session in the treaty's history.
There is a multipronged crisis: the expansion of nuclear arsenals by existing nuclear powers, rising proliferation risks, a fragmented and ineffective treaty-based nuclear governance regime, and the demonstrated failure of conventional military intervention to curb nuclear proliferation, as seen in the ongoing US–Iran conflict. This alters the incentive structure for non-nuclear states when it comes to effective nuclear deterrence, especially for the Arab states in the Middle East and allies in Europe, where regional risks are compounding, and reliance on the US is proving to be an unsustainable strategy.
Whether more countries pursue an independent nuclear path or nuclear-sharing arrangements as the way forward, the risk is of a diffuse nuclear arms race. This makes the ongoing 11th RevCon perhaps the most critical session in the treaty's history. If the 2026 RevCon fails to overcome the roadblocks that stalled the 2015 and 2022 RevCon sessions, the NPT will likely be remembered not as a “cornerstone,” but as a temporary truce in an era of inevitable nuclear proliferation.
Lavanya Mani is a Fellow at the Observer Research Foundation.
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Lavanya Mani is a Fellow at ORF, where she plays a key role on the curatorial team, shaping the thematic direction and programming of ORF’s ...
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