https://truthout.org/articles/iran-had-the-legal-right-to-shoot-down-us-spy-drone/ On June 19, an Iranian surface-to-air missile shot down an unmanned U.S. surveillance drone. The White House claimed that its drone was at least 20 miles from Iran, in international airspace, while Iran maintains the drone was in Iranian airspace. Iran presented GPS coordinates showing the drone eight miles from Iran’s coast, which is inside the area of 12 nautical miles that is considered Iran’s territorial waters under the U.N. Convention on the Law of the Sea.
Iran has the legal right to control its own airspace. The United States has no lawful claim of self-defense that would justify a military attack on Iran.
Both the U.S. and Iran are parties to the Chicago Convention on International Civil Aviation, which provides “that every State has complete and exclusive sovereignty over the airspace above its territory.”
Iran’s sovereignty over its airspace includes the right to shoot down an unmanned drone present without consent. “Although there is no black letter law on the question, state practice suggests that a state can use force against unmanned drones that have entered its airspace without consent,” Ashley Deeks and Scott R. Anderson wrote at Lawfare.