Europe’s streets were full of jubilant Iranians from the diaspora this weekend after US-Israeli strikes killed Iran’s Supreme Leader Ayatollah Ali Khamenei. “The dictator is dead. This is the best day of my life,” one man told DW as he danced through cobbled streets in Brussels.
Across town, EU officials remained critical of the Iranian regime. They have imposed a slew of sanctions on Tehran over human rights abuses and issued sharp rebukes of its recent retaliatory strikes on Gulf states. Yet EU governments now face a familiar diplomatic dilemma: were the US-Israeli strikes — which the Red Crescent says killed at least 555 Iranian civilians in addition to Khamenei — consistent with international law and the rules-based order the EU claims to uphold? EU spokespeople spent much of Monday’s briefing dodging that exact question.
President Donald Trump said the US was “ensuring that the world’s number one sponsor of terror could never obtain a nuclear weapon” and working to destroy Iran’s missile capabilities. His administration has not sought to justify the attacks through international frameworks. Defense Secretary Pete Hegseth said the US was acting “regardless of what so-called international institutions say” — with “no stupid rules of engagement,” and he criticized US “traditional allies” who “wring their hands and clutch their pearls.”
That stance will be received very differently across a divided EU. In Germany, Chancellor Friedrich Merz has been careful not to criticize Washington, saying legal assessments under international law “will achieve relatively little” in terms of political change in Iran and that “now is not the moment to lecture our partners and allies. Despite our reservations, we share many of their objectives.” By contrast, Spain’s Prime Minister Pedro Sánchez wrote: “We reject the unilateral military action by the United States and Israel, which represents an escalation and contributes to a more uncertain and hostile international order.”
Legal scholars are split. Marc Weller, professor at the University of Cambridge and director of Chatham House’s international law programme, argues there is “no available legal justification for the present, sustained attack on Iran.” He says international law does not permit the use of force in response to a hostile posture short of an armed attack, nor as armed retaliation for past provocations. Force, Weller writes, is permissible only as a last resort where no other means can secure a state from an armed attack. While humanitarian intervention to save a population from its own government can be argued, he believes Iran’s recent brutal crackdown on protesters “probably did not yet reach the threshold” to justify foreign intervention.
Rosa Freedman, professor of law, conflict and global development at the University of Reading, counters that legal texts must be read in context. “Law doesn’t operate in a vacuum,” she said, pointing to decades of threats from Iran across the region and clear statements about its nuclear ambitions. Read with the purpose of the UN and international law in mind, Freedman said, “those [US-Israeli] strikes within the context of Iran developing a nuclear weapon are completely lawful.”
Practically, the dispute over legality will largely remain academic because it is unlikely to be settled in court. The UN Security Council can impose sanctions or other measures, but the US can veto action against itself or its allies — as Russia has in other conflicts. As Freedman put it, “More powerful states are more able to do what they want to.”
Chatham House’s Weller warns that governments’ reluctance to call out unlawful conduct risks normalising the use of force as policy. That, he says, could have consequences for Europe: “It will not be easily possible to oppose further Russian aggression or potential Chinese expansionism if there are no clear principles left to rely on, without triggering objections of double standards and hypocrisy.”
The UN Security Council met to discuss the war, but divisions among powerful states make a unified response unlikely. The debate over legality, precedent and principle now sits at the center of a broader concern: whether Europe’s divided reaction will undermine its credibility and leverage on the world stage.
Xenia Polska and Finlay Duncan contributed to reporting in Brussels.
Edited by: Carla Bleiker