The revelation last September of Iran's subterranean uranium-enrichment lair in the holy city of Qom is but one piece of a vast network of underground mazes and hidden militarization, The New York Times reports. Tehran calls it "passive defense," and American analysts are having trouble estimating how far the black holes go. While Tehran's power is scattered dealing with domestic unrest, the Obama administration had hoped to push forward with a diplomatic campaign to reduce Iran's military might. But the presence of "hundreds, perhaps thousands, of big tunnels"—particularly those of dubiously private ownership—is holding back American intelligence agencies' ability to assess the situation. Iran is moving full speed ahead on the construction of tunnels and denies that they have military purposes; President Mahmoud Ahmadinejad began his professional life as a transportation engineer, and oversees much of the tunneling, including major projects that are owned privately by members of the Islamic Revolutionary Guard.