Cross section of Vietcong tunnels showing thier complexity and structure.
Classic Vietcong pitfall trap; a thin leaf cover would give way when a soldier stepped on it. Traps like these weren't designed to kill, but rather to slow down troops and psychologically scare them.
The Vietcong utilized guerrilla warfare to negate the technological superiority of the United States. They avoided large battles, preferring hit-and-run ambushes and booby traps, like punji stakes hidden in pits in the ground. The most legendary strategy was the Cu Chi tunnels, a vast underground network spanning hundreds of miles that had living quarters, hospitals, supplies, wells, torture chambers, and traps—all while only being accessible to shorter people, making it hard for widespread U.S. entry into the tunnels. These tunnels allowed them to vanish quickly after an attack.
Intresting Simple History video on the types of traps used by the Vietcong.