I believe it may be a vision
I see it as a foreshadowing of the enevitable apocolypse following World War 3. The blood of those died evaporates forming a red hue in the sky. Trees are scorched from a nuclear blast which also destroys the wall. The nets are cloaked devices that are booby trapped so that vehicles caught in them would be destroyed. If this is of any help, give me a personal message on your insight of my interpretation. Oh and great film; very dream-like.