Since the start of the second Intifada, tunnels dug beneath the Gaza Strip have become an underground highway for Palestinian militants and their weapons. "Israeli security forces have uncovered more than 100 tunnels, some as long as 800 meters, as deep as 15 meters" in the last four years, Defense News' Barbara Opall-Rome notes.Now -- even with signs of tensions cooling -- the Israelis are trying a blend of tactics and technology to try to close off the tunnels.
IDF will soon acquire... 100-ton vehicles known here as the Trencher to rapidly dig tunnels and ditches. Water-filled trenches, which seep into the soft, sandy soil of the Rafah border area, can collapse tunnels lying underneath.Defense and industry experts say acoustic, seismic, thermal and other sensors promise to help as well.One potential solution, by Herzliya, Israel-based Hadas Detection and Decoding, is intended to detect tunnels more than 20 meters underground. Known as the Underground Fence Solution or the UltraFence, and marketed by Rafael Armament Development Authority, the system analyzes acoustic noise and seismic changes to distinguish types of underground activities such as digging, walking or motorized movement...The other system under evaluation uses underground seismic antennas. Developed by Electro-Optic Research and Development (EORD), a national laboratory affiliated with Israel's Technion University in Haifa, the system filters out noise to determine the precise nature and location of underground threats...While many struggle to devise technological solutions, a senior operations officer suggested Israel might consider a Palestinian tactic.Since late January, when the Palestine Authority assumed responsibility for security in Rafah, Palestinian security forces have uncovered and destroyed two arms-smuggling tunnels. In at least one of those instances, local security officials filled the tunnel with raw sewage."When we go in and destroy tunnels, it's sometimes only a matter of time until the debris is cleared and the tunnel is reopened for business. But they filled the tunnel with [excrement], which totally clogged all the air holes for breathing. That tunnel won't be used for years," an IDF officer said.