Explained: Hamas's vast network of underground tunnels One of the stated missions of the Israeli airforce in the four weeks since the war broke out has been destroying Hamas infrastructure in Gaza through aerial bombardment. A key target has been Hamas's vast network of underground tunnels, which enable it to smuggle and stockpile weapons. But Israeli ground forces are likely to be needed to clear out the tunnel network known as "Gaza's Metro", according to former US officials and military officers. Bradley Bowman, a former US army officer and national security adviser, told our US partner network NBC: "A significant...