Expert SpeakRaisina Debates
Published on Jun 30, 2026
The legitimacy of military intervention over alleged weapons of mass destruction ultimately depends as much on credible verification as on international law
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The recent conflicts in Iran, attributed to its nuclear programme, and in Syria, along with the uncovering of the Assad-era chemical weapons programme, serve as constant reminders of how domestic unrest can escalate into a larger geopolitical conflict. These conflicts represent a consistent theme in geopolitics: the use of Weapons of Mass Destruction (WMD), specifically nuclear and chemical weapons, as a precursor to military intervention. The question, as ever in geopolitics, remains: how far can another state’s intervention be justified? What are the limits to, and the preconditions for, such intervention being justified? The controversy and general public distaste surrounding such justifications stem from a lack of reliance on verification mechanisms and a grey area in international legal norms.
Legal Framework Governing Use of Force
The primary legal foundation governing the use of force in international relations is the United Nations Charter. Article 2(4) prohibits the use of force against the territorial integrity or political independence of any state, establishing a general prohibition on unilateral military action. Further, Article 51, which exists as an inherent exception to Article 2(4), permits states to use force if an armed attack occurs, until the Security Council takes the measures necessary to maintain international peace and security—permitting self-defence, but not an attack. Beyond these articles, action under Chapter VII is authorised by the United Nations Security Council (UNSC), which determines the existence of a threat to peace, a breach of the peace, or an act of aggression, prioritising non-military measures over military action in the case of threats.
Outside of the UNSC’s Chapters and Articles, there are verification mechanisms for different WMDs. Institutions such as the International Atomic Energy Agency (IAEA) and the Organisation for the Prohibition of Chemical Weapons (OPCW) provide the evidentiary infrastructure through which compliance with treaties such as the Nuclear Non-Proliferation Treaty (NPT) and the Chemical Weapons Convention (CWC) is assessed. Such verification techniques are highly dependent on the cooperation of states, physical access, and continuous monitoring; when these conditions are disrupted, the level of certainty required for legal or political decision-making is compromised.
Despite these existing frameworks, WMD-related interventions have often been justified within this legal architecture by framing proliferation as a “threat to international peace and security,” or by invoking anticipatory self-defence (often referred to as the Caroline Standard, based on the 1837 Caroline affair on the US-Canada border), though such justifications remain highly contested
The Iraq Case
The 2003 US invasion of Iraq is the most studied case of WMD justifications being used as a rationale for military intervention. The US and some of its allies claimed that Iraq had a programme for the development and possession of WMDs, in contravention of UN Security Council resolutions. Post-war investigations found no WMD stockpiles, which further undermined the rationale for the war. The Iraq Survey Group found that Iraq had curtailed its WMD programme in the 1990s. The case thus brought to light serious problems related to the interpretation of intelligence.
The US and some of its allies claimed that Iraq had a programme for the development and possession of WMDs, in contravention of UN Security Council resolutions
From a legal standpoint, too, the case raised many disputes regarding how far the United Nations Security Council’s authorisation for the use of force extended, and whether existing UN resolutions could serve as a legal basis for the use of force in 2003. The absence of a new UN resolution on the matter fuelled discussions on the interpretation of earlier resolutions
The Syrian Case
Another, more recent case of weapons-use verification is the Syrian civil war, which offers a different kind of lesson about verification mechanisms amid an active war scenario. After reports of chemical weapons use in Syria, the OPCW was tasked with investigating the incidents and determining the responsible parties, through its Fact-Finding Mission and Investigation and Identification Team
Although the OPCW confirmed numerous cases of chemical weapons use, it faced certain difficulties owing to the ongoing conflict, including an inability to fully access some of the sites in question, which affected the process of on-site verification. The Syrian case shows that even the existence and operation of international verification mechanisms do not guarantee full functionality amid war
From a legal perspective, the confirmed use of chemical weapons constitutes a clear violation of the CWC. The Syrian case therefore illustrates a broader structural issue: technical verification mechanisms can produce credible findings, but holding violators accountable still depends on effective enforcement
The Iran Case
The Iranian nuclear programme, and the US-Israel response to it, represents a more contemporary case in this debate. Under the NPT framework, Iran is subject to IAEA safeguards designed to ensure that nuclear material is not diverted for military purposes
In recent years, and particularly following intensified regional conflict beginning in 2025 involving strikes on nuclear-related infrastructure, IAEA verification capacity has been significantly affected, limiting inspectors’ access to certain facilities. As a result, the continuity of monitoring has been disrupted by both physical damage and political constraints. Despite this, the IAEA has stated that there is no confirmed evidence of an active nuclear weapons programme in Iran, while also acknowledging that verification gaps have widened due to these access limitations.
The Iranian case thus highlights a key systemic challenge in modern non-proliferation regimes: constraints on verification mechanisms, whether from state non-cooperation or the limits imposed by conflict, can weaken the evidentiary basis for decision-making
From a legal standpoint, concerns over Iran’s nuclear activities are typically addressed under the UN Charter through UNSC resolutions and questions of compliance with the NPT. The difficulty here is that incomplete verification data makes it harder for the Security Council to translate scientific uncertainty into the legal threshold required for Article 39 determinations on the use of force
The Iranian case thus highlights a key systemic challenge in modern non-proliferation regimes: constraints on verification mechanisms, whether from state non-cooperation or the limits imposed by conflict, can weaken the evidentiary basis for decision-making
Comparative Lessons Across Cases
A comparative reading of Iraq, Syria, and Iran highlights three recurring structural challenges
1) Verification processes play an important role in establishing a factual baseline for analysis, yet remain prone to interference. In Iraq, verification gaps emerged before the intervention, owing to flawed interpretation of intelligence. In Syria, verification was hampered by ongoing hostilities. In Iran, verification gaps stem from both restricted access and damage to nuclear infrastructure
2) The relationship between verification findings and their legal weight under the UN Charter is rather indirect, yet significant. The Security Council’s determination of a threat to peace under Chapter VII typically relies on expert assessments from organisations such as the IAEA and OPCW. Any deficiencies in such assessments introduce ambiguity into the legality of any resulting collective action
3) WMD suspicions often affect the timing of the decision-making process, and can come into tension with verification procedures that are inherently time-consuming and consensus-based
International verification regimes are designed to minimise uncertainty rather than eliminate it entirely. Their success therefore depends on access, cooperation, and operational stability. When any of these elements is compromised, verification yields a provisional conclusion rather than an absolute one
Self-defence claims under Article 51 rest on findings of imminence and necessity, while Chapter VII interventions are justified by the Council’s determination of a threat
This has significant consequences for the law underpinning the UN framework. Self-defence claims under Article 51 rest on findings of imminence and necessity, while Chapter VII interventions are justified by the Council’s determination of a threat. Both these processes presume the existence of reliable information, something that is often difficult to obtain in the WMD context, owing to secrecy or conflict
Conclusion
The recurring role of WMD allegations as a trigger for hostilities points to a structural contradiction within the international security regime: the system relies on verification mechanisms whose reliability is least assured precisely when the stakes, and the temptation to act without full evidence, are highest. Taken together, the Iraq, Syria, and Iran cases show that the legitimacy of decisions on the use of force, where alleged WMDs are concerned, hinges not only on legal considerations under the UN Charter, but equally on the integrity of the verification process underpinning them. Strengthening this process through sustained access, institutional independence, and a clearer link between technical findings and legal criteria remains essential to ensuring that decisions on the use of force rest on credible evidence.
Shravishtha Ajaykumaris an Associate Fellow with the Centre for Security, Strategy, and Technology at the Observer Research Foundation
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Shravishtha Ajaykumar
Shravishtha Ajaykumar is an Associate Fellow at the Centre for Security, Strategy, and Technology. Her research areas include Chemical, Biological, Radiological, and Nuclear (CBRN) strategy
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The WMD Dilemma: Verification, Legality, and Military Intervention
International Affairs
Jun 30, 2026
