When reports emerged in August of an alleged Iranian plot to assassinate President Donald Trump during a NATO summit in Turkey, much of the ensuing debate centered on the credibility of the intelligence. The CIA reportedly had low confidence in Israeli-sourced information suggesting Iran planned to fire a surface-to-air missile at the president's aircraft. But the more profound question—whether a sovereign state should ever plot to kill the leader of another sovereign state—received far less scrutiny.
For most of the modern state system, a normative prohibition on assassinating foreign leaders has been a cornerstone of international order. This norm, rooted in the Westphalian system, was designed to regulate interstate violence and preserve sovereign equality. It was codified in the Hague Conventions of 1899 and reinforced by Additional Protocol I of the Geneva Conventions, which banned "treacherous" killing and acts of "perfidy." While the legal language was never airtight, its political force was unmistakable.
The practical rationale was simple: by channeling conflict toward the battlefield, wars would be decided by the organized capacity of states—their armies, economies, and logistical depth—rather than by the targeted elimination of decision-makers. This suited great powers, which historically viewed assassination as the weapon of the weak. Even during the Cold War, when covert operations against foreign leaders were common, plausible deniability preserved a semblance of normative compliance.
The humanitarian exception
The first sustained assault on this taboo came through a humanitarian argument. Throughout the 1990s and 2000s, proponents argued that removing a brutal dictator could spare entire populations the horrors of conventional war. Saddam Hussein and Muammar Gaddafi became test cases. Assassination attempts were made against Saddam during the Gulf War, and multiple plots targeted Gaddafi. When conventional operations eventually removed them, the humanitarian framing was part of the justification.
The empirical results, however, repudiated the argument. Iraq and Libya both descended into state collapse, civil conflict, and humanitarian catastrophes that dwarfed the costs of the authoritarian orders they replaced. Even defenders of coercive humanitarianism conceded that these cases blurred the line between civilian protection and regime change. The political function of the humanitarian argument was to legitimize tyrannicide, making the targeting of foreign leaders appear morally defensible and, eventually, actionable.
This shift in moral vocabulary allowed a distinction to emerge between "targeted killing" and illegal "political assassination." That distinction enabled states, particularly the United States, to present extraterritorial killings as reviewable and therefore legitimate.
Falsified self-defense
The killing of Qasem Soleimani, Iran's top general, by an American drone strike in Baghdad on January 3, 2020, marked a turning point. Soleimani was a senior uniformed official of a sovereign state, killed in the territory of a third state without a declared war. The US not only acknowledged the strike but publicly defended it as anticipatory self-defense. This open embrace of decapitation as statecraft set a dangerous precedent, reducing the reputational cost for other states contemplating similar actions.
More recently, the killing of senior Iranian leaders, including the supreme leader, in the opening phase of a US-Iran conflict has institutionalized leadership decapitation as an operational doctrine. This erosion of norms is not confined to the Middle East. In the Indo-Pacific, where great-power competition is intensifying, the acceptance of assassination as a tool of statecraft could have profound implications. As US wartime buildup races against China's industrial clock, the temptation to target adversaries' leaders may grow.
The norm against leadership assassination was never perfect, but its erosion threatens the stability of the international system. If states can openly plot to kill each other's leaders, the distinction between war and peace blurs, and the risks of miscalculation rise. For Asia, where historical rivalries and territorial disputes remain unresolved, the collapse of this norm could turn diplomatic crises into existential confrontations. As Iran's leadership vacuum turns the Strait of Hormuz into a geopolitical void, the lesson is clear: when the taboo falls, no leader is safe.
