Usually the topic of potential casualties comes before the strike decision. Indeed, it is usually the first point before choosing a response option. Somehow the US got very close to a retaliatory strike before establishing the basics. Unbelievably, POTUS is now providing the excuses for Iran by declaring that the original shoot-down was not orchestrated at Iranian government level, suggesting it was someone much lower down. He also seemed to suggest that shooting down an unmanned aircraft in international airspace was more excusable due to the absence of people.
So does the US feel the need to respond to a SAM attack on an expensive aircraft or not?