huh?
The way you wrote your sentence it says “no one can doubt that the missile downing the airliner was an intentional act.”
The plain reading of that is that they intentionally downed an airline.
It was a war zone. The airliner encroached on that war zone and was targeted. The missile was intentionally fired at that target...that happened to be an airliner. I guess I could have called it a UFO, but I already knew it was an airliner. Downing the UFO was an intentional act. Targeting and firing on any aircraft with that particular weapons system is not accidental.