Although military planners are frustrated by a vast web of tunnels and underground bunkers in Iran, tunnel-boring manufacturers find the country a booming market. Subways, highway tunnels and water tunnels are all being built. However, some say Iran's nuclear experiments are protected by the tunnels as well. The details are hazy, but satellite images have shown Iranian contractors creating vast caverns the size of the Pentagon, and some mountains are now believed to be honeycombed with huge networks of tunnels and bunkers.
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