The plan was to bomb this bridge which was an escape route for North Vietnames forces escaping from the bombing in Cambodia. This photo and a few others like it had to be cleared by military intelligence (you know that joke already) who said exactly this: "That is a damn good picture of that bridge being bombed. In fact, it is the best picture I have ever seen of a bridge being bombed. But you can't release it because the United States Air Force does not bomb bridges!" So this picture was never released and therefore this bridge was never destroyed. (Do you think anyone has found out yet?)