Nonsense!
There is no such thing as a “self-defense strike” when you are the initial aggressor. No state can invoke self-defense while stationing helicopters and drones along another country’s borders for the purpose of enforcing an unlawful naval blockade, systematically and repeatedly violating that country’s airspace, particularly when the entire operation is being conducted 8,000 miles from its own mainland.
Any military action undertaken by the initial aggressor in response to a state’s lawful exercise of self-defense is not "defensive" by any standard. It is merely a continuation of the original unlawful use of force and act of aggression.
Furthermore, attacking Iran’s water infrastructure in response to the downing of a single intruding helicopter cannot plausibly be described as “proportionate” either. Such an attack constitutes a serious war crime, both because it violates the principle of proportionality and because of the civilian nature of the targets.
U.S. Central Command (CENTCOM) forces began launching self-defense strikes against Iran at 5 p.m. ET today at the Commander in Chief’s direction, in response to yesterday’s downing of a U.S. Army Apache helicopter. The mission is a proportional response to unjustified Iranian aggression.