When Hamas released two elderly hostages last week, one of them described being led miles through a "spider's web of tunnels" that eventually led to a large hall, per the Guardian. It's no surprise: The militant group is known to maintain a labyrinth of tunnels beneath Gaza nicknamed "the Metro" by Israeli defense officials. The tunnels pose an immense military challenge, in part because their true extent isn't known, and they may help explain the delay in a wide-scale ground invasion. Coverage:
- Expansion: Tunnels beneath Gaza have existed for decades, but the New York Times explains that they've been greatly expanded since Israel tightened its blockade of Gaza in 2007 and Hamas gained control of the enclave. By some estimates, Hamas has about 300 miles of tunnels, many of them shored up with concrete and iron to withstand bombardments. Last week, Israel destroyed a tunnel beneath a beach designed to allow Hamas to attack by sea, a whole new front of this type of warfare.