This is an actual reconnaissance photo I took over Laos. The Ho Chi Minh trail was not one trail but a series of paths, highways, and bridges making their way South from North Vietnam. Here you can see a couple of underwater bridges. An F-4 (circled) has just put in an airstrike in the bottom of the photo I think he was trying to hit on of the underwater bridges...don't remember. Maybe something else. You can see the area around there is pretty pocked with previous air strikes.