Editor's note: Tian Shichen is the founder and president of the Global Governance Institution. The article reflects the author's opinion and not necessarily the views of CGTN.

As the US-Israeli strikes on Iran continues without resolution, the international community faces a pressing question: Is this war legal? The United States has justified its strikes as "necessary and proportionate" acts of collective self-defense under Article 51 of the UN Charter. Yet a rigorous legal analysis suggests that the current operations struggle to meet the strict thresholds established by international law.

A primary justification for the conflict has been the need for "preemptive action" to protect personnel from potential Iranian retaliation. Legally, however, this argument is tenuous. Under the UN Charter, the use of force is lawful only in response to an actual or imminent armed attack, or with explicit Security Council authorization.

The standard for "imminence" is guided by the long-standing Caroline test: the threat must be instant, overwhelming, leaving no choice of means, and permitting no moment for deliberation. Speculative risks or potential future capabilities do not justify the use of force. Internal reports suggesting limited intelligence on an imminent threat further weaken the legal basis for preemptive action.

The ongoing military strikes also complicate the broader legal landscape by undermining diplomacy. Engaging in hostilities while negotiations are underway violates the principle of good faith under the Vienna Convention on the Law of Treaties. Such actions erode international trust and constitute an abuse of rights –a principle recognized as far back as Ancient China, where harming envoys of belligerent states was strictly prohibited.

Even if the jus ad bellum–the right to go to war–is questionable, the conduct of operations under jus in bello (International Humanitarian Law, IHL) remains equally critical. IHL applies impartially to all parties, regardless of who initiated the conflict.

Central to this framework is the principle of distinction: combatants must differentiate between legitimate military targets and protected civilians or civilian objects. Dual-use infrastructure, such as power plants, presents particular challenges. For a power plant to be lawfully targeted, it must make an effective contribution to military action and provide a definite military advantage if destroyed.

Even then, the principle of proportionality applies: an attack that causes excessive civilian harm–for instance, disrupting hospitals–violates the laws of war.

The role of neutrality is also at stake. Western support for regional allies–including intelligence sharing, use of bases for combat, or supplying specialized weapons–risks breaching the strict legal status of neutrality under the Hague Convention (V). Once a neutral state participates materially, it can become a lawful target itself, expanding the scope of the conflict.

Protecting the integrity of international law requires that violations carry tangible consequences, including diplomatic isolation and economic penalties. Major powers bear a special responsibility to lead by example, rejecting exceptionalism and selective rule application. Consistency is essential if international law is to retain its authority. Small and middle powers must coordinate to defend legal norms, ensuring that the global order is determined by the strength of law rather than the law of the strongest.