Thwarting the Tunnelers

Many years ago, my mother suggested the solution to Chernobyl before the disaster was addressed in exactly that way. Now, she has suggested that the infiltration tunnels from Gaza into Israel can be severed by digging a forty meter deep trench, wide enough to monitor and block any attempt to dig through from the Strip. This would seem to be a technically feasible and relatively cost efficient way to make it harder for jihadists to terrorize Israelis. A trench or even that trench being filled with water and turned into a modern moat would make Hamas' effort at digging tunnels a much more difficult undertaking without more risk to innocent life. As it is now, street to street and even house to house fighting extract a terrible toll on both sides. No one could argue a trench or moat is aggression. Israel can perform a purely defensive measure that ultimately will save lives not only in Israel but in Gaza as well by digging what amounts to a deep ditch.