The United States most likely committed an act of aggression against Iran and killed Soleimani in violation of human rights law. Here is why:

Aggression was originally defined at the Nuremberg Tribunal and was then later codified in part by General Assembly Resolution 3314 as well as by the International Criminal Court (ICC). The ICC uses a definition of aggression derived from international customary law, which generally prohibits the invasion or attack with a state’s armed forces against the territory of another state — including through bombing a state, blockading its ports and coasts, or sending irregular/partisan/paramilitary forces to accomplish the same.