The Legality of the Use of Interstate Force during the 2026 Israel/US-Iran Hostilities: What States Said and did not Say

In February 2026, a coordinated US and Israeli aerial attack on Iran led to regional hostilities, with Iran retaliating against both the initial aggressors and several uninvolved states. A fragile ceasefire was established on April 8, 2026. While experts largely viewed the initial US/Israeli attacks as violating jus ad bellum, international law remained central to states' analyses. UNSC Resolution 2817, supported by 135 UN Member States, condemned Iran's armed attacks against Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, the UAE, and Jordan, affirming their right to self-defense. The US and Israel justified their actions as continuous self-defense, while Iran claimed self-defense against aggression, admitting some attacks on territories used by the US for planning. Notably, there was a more robust condemnation of Iran's response than of the initial US/Israeli attacks, leading Iran to complain that the UNSC reversed the roles of victims and aggressors. The article explores the legal implications of this asymmetric condemnation and the significance of state silence in interpreting jus ad bellum, noting that silence can be influenced by various diplomatic and political factors beyond legal acceptance.