AP Photo

On 25 August, Israel put an end to Gaza's single most impressive feat of underground engineering. For the three days the tunnel was operational, traders were able to make use of the first fully functioning road in and out of Gaza since Israel imposed its siege after Hamas's electoral victory. The tunnel was cavernous, built to last, and had ramps allowing vehicles to drive in and out. Its sides were fortified with scrap iron taken by Gazans when, one winter day in 2007, they pulled down a small part of the eight-metre-high wall Israel had erected along much of Gaza's 14-kilometre border with Egypt.

Israel has recently targeted at least 13 tunnels, and Egypt has destroyed several more. The rain has caused others to collapse. This, and the fear of sabotage, has meant that the...