Why US Military Action Against Iran is Justified Under International Law
For nearly half a century, the Iranian regime has called for “death to America” and targeted Americans through terrorism, direct assaults, and proxy attacks. From the 1983 bombing that killed 241 American Marines in Beirut, to the Khobar Towers attack on US personnel in 1996, to the hundreds of US troops killed by Iranian-backed militias in Iraq, to the wave of Houthi strikes on US naval assets in the Red Sea and proxy attacks on US personnel in Iraq and Syria in recent years, Iran has waged a sustained campaign of hostilities spanning more than four decades-an anti-American campaign that began with the 1979 seizure of the US Embassy in Tehran and the 444-day hostage crisis.
Yet critics –including Joe Kent, several members of Congress and some European leaders–argue that US military action is unlawful because Iran “posed no imminent threat.” This claim views the risk of an Iranian attack as isolated and speculative, when it fact it is ongoing and fits within a long-established pattern of armed attacks.
This claim also reflects a fundamental misunderstanding of the legal standard. Under international law, imminence is not limited to an attack that will occur tomorrow. As Brian J. Egan, legal advisor to the US State Department under President Barack Obama, explained: “In the view of the United States, once a State has lawfully resorted to force in self-defense against a particular armed group following an actual or imminent armed attack by that group, it is not necessary as a matter of international law to reassess whether an armed attack is imminent prior to every subsequent action taken against that group, provided that hostilities have not ended.”
US government legal advisors, military law experts, and scholars of armed conflict have long recognized this principle: once a pattern of armed attacks rises to the level of an ongoing armed conflict, the framework shifts. The question is no longer whether the next attack is imminent. It is how to bring ongoing attacks to a decisive end.
Iran’s decades-long pattern of attacks meets the legal definition of an ongoing armed conflict, triggering the United States’ inherent right of self-defense under Article 51 of the UN Charter. As Mark Goldfeder, a professor of international law, and John Spencer, a former US Army officer and chair of urban warfare studies, explain: “Iran’s campaign against US military interests did not begin this week. It has spanned decades. The relevant legal and strategic question is not whether Tehran might one day act. It is whether a pattern of armed attacks, proxy operations, missile strikes, and assassination attempts already constitutes an ongoing armed attack under Article 51 of the UN Charter.”
Under this legal framework, when attacks are ongoing, Article 51 accords the United States the right of self-defense to bring those attacks to an end. As Geoffrey Corn, a retired US Army lieutenant colonel and military lawyer, and Orde Kittrie, a former State Department attorney, explain: “International law does not require a distinct self-defense justification for every attack conducted once the right of self-defense is triggered. Once that right is initiated, military action is justified to achieve the overall self-defense objective, in this case terminating Iran’s capacity to strike the United States and its allies.”
The United States is not initiating a new war with Iran. It is responding to – and seeking to end — a decades-long campaign of sustained Iranian aggression, a shadow war that began in 1979 and has continued through direct attacks and proxies ever since.
To insist that the United States wait until the moment before the next attack is not only a misreading of international law. It is a standard that would tolerate preventable harm to American service members and civilians as the price of inaction.
