The 51 kilometers of security fence separating Gaza's 1.2 million residents - and thousands of terror operatives - from the Israeli communities of the Negev has for years been the front line of a cat-and-mouse game between hi-tech monitoring solutions and years of planning and experimentation on the part of terror organizations. The touch-sensitive fence is patrolled multiple times a day, along a narrow road that parallels it. Beduin trackers like the non-commissioned officer killed Thursday morning play an integral part in those patrols, checking the sandy shoulders for footprints, signs of digging or any other suspicious change that could indicate terror activity. But the patrols along the fence are only one part of the system. Behind the patrol road, sometimes out of sight of the closely-guarded border area, spotters from the IDF's Intelligence Corps keep their eyes glued to screens monitoring the fence, and the area around it, 24 hours a day. In a task almost exclusively performed by female soldiers, it is the spotters who are responsible for most of the sightings along the fence, alerting tanks and infantry when they notice suspicious movement in the area. For every mine like Thursday's, which was planted without being noticed by the spotters, dozens of bomb-planting cells are observed - and then neutralized - before they ever plant their deadly cargo. Other bombs are spotted by the trackers on their patrols, and neutralized by IDF and police sappers before they can do damage. But when scenarios like Thursday's attack occur, both the IDF - and, apparently their adversaries - rely on experience not only from the past decade of cat and mouse along the fence, but also on lessons learned from another, similar fence, hundreds of kilometers to the north. Observers noted that the attack, for which the Islamic Jihad claimed responsibility, bore similarities to attacks carried out by Hizbullah against IDF patrols along the Lebanese border. Similar to ambushes along key routes in southern Lebanon prior to the 2000 pullout, the explosive device that was detonated Thursday seems to have been activated by remote control, while operatives waited, hidden, to ambush both the wounded as well as any troops who came to their rescue. But the IDF also changed its behavior along the fence as a result of the lessons learned along the northern border. Since 2006, the vehicles carrying out the patrols in tandem have begun to keep a wide berth between them, in order to ensure that any attack against one of the vehicles will not necessarily paralyze the second vehicle as well.