David Leonhardt and Lauren Jackson wrote this morning(in NYT) about HAMAS' underground world in Gaza created as a response to Israeli aerial bombs. The network is extensive and allows terrorists goons to hide in relative security during air raids.
Tunneling for protection and security is nothing new in warfare tactical and strategic planning, especially today with vast technologic -capabilities around the world, even in the hands of terrorists like HAMAS. History is replete with stories of tunneling. As example, the Vietnamese Communists were driven to excavate vast underground complexes not only for fighters, but their families and villages alike. The famous tunnels of Cu Chi offer classic tours of these underground maze-like structures that survived the American War in SE Asia over 50 years ago. On a recent tour there, the Mayor observed some of these hiding places.
During WW II, the Nazis and German engineers sought fortifications that could withstand aerial bombardment in many places, including the well known Atlantic Wall in western France. The southern limit of the Wall bumped up against the Pyranees Mts. of Spain/France. Often, the Nazis repurposed Medieval forts due to their strategic positions. An example in this case is found in the port city of St. Malo. The Mayor recently on tour in the area was able to examine the interior of this WW II relic. The engineering was incredible despite being constructed/reconstructed during wartime. Over the top of the fort in places, was solid concrete, steel reinforced, that was 18' or 15 m. thick. Despite being hit directly by aerial bombs, the interior was never breeched. The key to survival underground is, of course, ventilation: intakes and exhausts. The Nazis had electric fans providing both and were capable of operation w/o electricity in the event of failure.
On the Bay of Biscay Coast of France, Nazi architects built covered berths for the Atlantic U-Boat flotilla that had formerly docked in Germany. This advantage led to the destruction of much Atlantic ocean shipping prior to May, 1942. While the lids on these "sub pens" were not as strong as Atlantic Wall positions, it did offer limited protection.
These historic lessons were not lost to HAMAS of their Palestinian and Iranian friends.