海角大神

Israel says that dozens of tunnels now snake underneath its heavily patrolled border with Gaza and present its military with a new challenge that its current offensive is designed to neutralize.

Israel Defense Forces (IDF) officers say the network of underground bunkers and tunnels gives Hamas rare access to Israeli territory, a threat not to be tolerated. 鈥淭he main goal right now is to locate and destroy tunnels that lead into Israel,鈥� says Maj. Gen. Gadi Shamni (res.), a former commander of the Gaza division, calling the tunnel threat 鈥渟evere.鈥�

Yesterday the IDF thwarted a聽cross-border tunnel attack by 13 Hamas operatives on an Israeli kibbutz, and Israeli Prime Minister Benjamin Netanyahu has said the focus of the ground invasion is to destroy such tunnels. Most reports indicate that troops are focused on a narrow corridor along the Israeli border.

The geological makeup of the area and the potential for surprise attacks all make the tunnels a big challenge for the IDF. Back in 2009, when Israel last launched a ground invasion on Gaza, the main tunneling front was along the Gaza-Egypt border, mostly for smuggling. The tunnel used聽in the kidnapping of聽Israeli soldier Gilad Shalit in 2006 was adjacent to that area, but now a new front has developed on the Israel-Gaza border.

鈥淭his is one of the new things that has been implemented,鈥� says Miri Eisin, a former military intelligence officer who served as a government spokesman during the 2008-2009 war. 鈥淏ecause of that it鈥檚 really the major challenge.鈥�

Although ground troops can identify and destroy concealed entrances, it can be difficult to pinpoint a tunnels' route and branches. And while numerous detection systems exist, distinguishing between natural holes in the sandy area and man-made tunnels isn't easy, says Col. Eisin (res.).聽

鈥淏ecause the land is so porous it鈥檚 hard to distinguish,鈥� she says, even when the tunnels are reinforced with man-made materials. 鈥淐oncrete doesn鈥檛 show up on most of the different kinds of sensors that you have. And that鈥檚 part of challenge. You actually have to go to find openings and go in.鈥�

Copying Hezbollah

Hamas鈥檚 tunnel network follows the successful use of tunnels by Hezbollah against an Israeli incursion into Lebanon in 2006.

The Lebanese Shiite militant group built its first prototype of an underground bunker in the mid-1980s, which can be seen today at its tourist museum in Mlita, Lebanon.

But it wasn鈥檛 until Israel鈥檚 withdrawal from south Lebanon in 2000 that聽Hezbollah聽began building up an extensive system of underground bunkers and rocket launchers, with an estimated 1,000 facilities by the time of the 2006 war between Israel and Hezbollah. During the fighting, some massive underground networks were found, including one with air conditioning, a cafeteria, dorms, medical facilities, and 3-foot-thick cement ceilings 鈥� all built聽secretly聽in view of a United Nations outpost along Israel鈥檚 border.

Some of Hezbollah鈥檚 bunkers are so well-hidden that even with GPS coordinates that lead to within 10 feet of the entrance, they can be hard to spot. While some have been abandoned, Hezbollah is believed to be building even larger facilities, big enough to drive a truck into.

Many Israeli analysts say that Hamas gleaned its tunnel-building expertise from Hezbollah, though it is unclear whether they traveled to Lebanon, hosted Hezbollah operatives in Gaza, or shared knowledge remotely.

The tunnels have allowed both militant organizations to build up their rocket capabilities and preserve an element of surprise in their attacks against Israel, though Hezbollah鈥檚 capabilities far outweigh those of Hamas.聽

Detecting Hamas tunnels聽聽聽聽聽聽聽聽聽聽聽

Last fall, Israel discovered and destroyed a mile-long tunnel built more than 60 feet under the border over the course of about a year.聽聽An officer who formerly served in the IDF鈥檚 geology unit that it was professionally done and heavily reinforced with concrete. The fossilized sea shells and deeper water table in that part of Gaza make it more conducive to tunneling, the officer said.聽

Methods for detection include radio monitors that can indicate cavities and seismic tools that pick up on movement underground 鈥� though those can become overwhelmed with the usual bustle of life above the ground.

The IDF reportedly found five tunnels by midday today and it estimates there are dozens more. While a ground presence helps find tunnels, it also increases the risk of Israeli casualties.

鈥淭he decision to go in 1 to 2 kilometers (0.6 to 1.2 miles) is our decision. But once you鈥檙e in 1 to 2 kilometers and you stay there, you鈥檙e sitting there and you鈥檝e become targets that you were not before,鈥� says Col. Eisin, noting that the rocket fire that prompted Israel鈥檚 escalation is likely to continue. 鈥淯nless you physically conquer all of the Gaza Strip, which takes longer than a week 鈥� until the last day there will be firing of rockets.鈥�