If authorized by the appropriate military channels (i.e., from the head of state, or someone legitimately acting on behalf of the head of state), yes, this would be an “act of war.” As it stands, it was most likely a “crime.”
Depends on your definition of “crime”.
To me, it was a crime against the USA and its citizens.
To the Community Organizer-in-Chief: the crime against the USA was justified by a ‘crime’ against one of the religions of the world.