Under the cover of darkness, IDF Engineering Corps troops from Battalion 603, backed by armored D-9 bulldozers, crossed the security fence along the Israeli-Lebanese border north of Avivim late Wednesday night to sweep the area for booby traps and Hizbullah bombs. The soldiers did not cross the actual international border - which is several meters north of the security fence - and remained inside Israel throughout the duration of the operation. There was nothing overly unique about IDF troops crossing the fence. Since the end of the Lebanon war last summer, OC Northern Command Maj.-Gen. Gadi Eizenkot has ordered dozens of similar operations, during which troops have found Hizbullah-planted bombs, guerrilla bunkers and hidden weaponry. What was interesting about this operation, however, was its outcome. In the afternoon, the IDF liaison office in the Northern Command informed UNIFIL of the planned operation and stressed that while the troops planned to cross the fence, they would not cross the Blue Line and set foot inside Lebanon, an act that could be interpreted as an invasion. The response was quick to come, and the Lebanese Armed Forces relayed a message back through UNIFIL in which it threatened to open fire at IDF troops if they crossed the security fence. Following consultations at Northern Command headquarters in Safed, as well as with outgoing Chief of General Staff Lt.-Gen. Dan Halutz and Defense Minister Amir Peretz, a decision was made to move ahead with the operation, despite the threat and slim possibility that clashes along the northern border could lead to a conflict with Lebanon and/or Hizbullah. Late Wednesday night, the soldiers and bulldozers entered the border enclave and began sweeping the area while ensuring not to cross the Blue Line. After about an hour of work, Lebanese troops stationed nearby opened fire. The IDF's response was immediate. A Merkava tank fired two shells at a Lebanese position and wounded several of the soldiers. The decision to respond severely was a difficult one to make, but was calculated and took into consideration the possibility that it could lead to a renewal of Hizbullah's Katyusha rocket fire. Eizenkot and Halutz decided that Wednesday night's incident needed to be used to set an example. During the consultations at the Northern Command, Eizenkot said: "By returning fire, we are making it clear that Israel is not willing to put up with this type of conduct." By returning fire, he continued, Israel was sending a clear message to Hizbullah and the Lebanese that the policy prevalent along the border during the six years before the war was no longer in effect and from now on, the IDF would operate freely along the border and not be restricted by Hizbullah or Lebanese dictates. Following the withdrawal from Lebanon, Israel pretended that the area between the security fence and the Blue Line was not its territory, and allowed Hizbullah to take up positions there. Following the war, Prime Minister Ehud Olmert's government made a decision not to repeat that mistake - and Wednesday night's operation made that clear to Hizbullah. WHILE THE situation might be changing in the North, the same cannot be said about the Gaza front where, since November, the IDF has kept its finger off the trigger, despite daily Kassam rocket attacks and violations of the so-called Palestinian cease-fire. Hizbullah and Hamas are both preparing for war. Hizbullah gets its weapons in truckloads funded by Damascus and sent across the Syrian-Lebanese border. Hamas gets its weapons from Sinai via tunnels under the Philadelphi corridor in the southern Gaza Strip. Both fronts pose major security threats to the State of Israel: The Palestinians are working to advance their rocket array, and Hizbullah is said to almost be back at the level of strength it maintained before the Lebanon war. The fronts also pose a major diplomatic predicament for Olmert and his government. Olmert is well aware that a continuation of the tense standstill will only further strengthen the terror groups, which despite the cease-fire in Gaza and the strong presence of UNIFIL and the Lebanese in southern Lebanon, are continuing to build up militarily. On the Gaza front, the defense establishment is aware that without a major diplomatic breakthrough, a widespread ground operation is just a matter of weeks away. OC Southern Command Maj.-Gen. Yoav Galant has been pushing for such an operation, as has Defense Minister Amir Peretz, who has repeatedly called for an end to the policy of restraint in face of the almost-daily Kassam rocket attacks. On the other side of the spectrum is Shin Bet (Israel Security Agency) chief Yuval Diskin, who said this week that Israel needed to demonstrate patience and "not run to launch an operation in Gaza." While claiming that Israel "needed to prepare contingency plans," he said that now was not the time for an operation even though Hamas was growing stronger by the day. He conceded that as time passed, if not dealt with, Israel would find itself facing a Hizbullah-like force in the Gaza Strip, with advanced rocket and military capabilities. That is the feeling in the Northern Command as well. While the border is quiet - except for the five bombs discovered along the Blue Line this week and the isolated clashes Wednesday night - Eizenkot has, in private meetings, predicted that there is a possibility of another round against Hizbullah by this summer. While the prevalent assumption in the defense establishment was that Hizbullah wanted a "period of quiet" to rehabilitate its military infrastructure, the discovery of the five bombs along the border - believed by the IDF to have been planted recently - might prove otherwise. The IDF is preparing for the possibility that Hizbullah is returning to full-fledged terror activity and is getting ready to respond with full force if and when it is given the green light by Olmert. With regard to Gaza, Diskin raises a number of parameters that need to be taken into consideration before launching an IDF operation. The first is the ongoing factional violence, which he recommends Israel stay clear of. The second question to be considered is what will happen the day after the operation. Will the IDF remain in the Gaza Strip or just spend a few weeks there and then leave? If the Palestinian Authority collapses, will the IDF reestablish the civil administration and began providing social services to the population? Or will the government walk away from Gaza and once again enable the terror groups to rebuild themselves until the next operation? This quandary is what Gabi Ashkenazi will step into on Tuesday when he takes over as chief of General Staff.