Monday's attack near the Karni border crossing, which was claimed by the Army of Islam group, shows that Hamas still doesn't have full control over the Gaza Strip. Hamas officials said they were surprised by the attack, which came as leaders of the Islamic movement started arriving in Cairo for talks with Egyptian officials on ways of ending the power struggle with Fatah and maintaining the relative calm in the Strip. One Hamas official said he did not rule out the possibility that the latest attack was aimed at scuttling the Egyptian mediation efforts and embarrassing his movement. Noting that Hamas was keen on preserving the current relative calm, he said that Hamas was trying determine the identity of those responsible for the attack. Over the past few months there have been periodic reports that Hamas's security forces had blocked attempts by other groups to fire rockets and mortars at Israel. In some incidents, Hamas reportedly arrested Palestinians who defied its orders. The Army of Islam has in the past been targeted by Hamas, especially after its members carried out numerous bombing attacks on cafes and restaurants in the Gaza Strip. Hamas has shown that it has little tolerance for competition from other groups. Some Palestinians, however, believe that the attack could not have been carried without the approval or knowledge of Hamas, whose security forces and supporters are scattered throughout the Gaza Strip. A former Fatah security officer said he did not rule out the possibility that the assailants belonged to one of Hamas's militias. Hamas, he added, may have sought to distance itself from the attack after it transpired that the terrorists had failed to kill or kidnap IDF soldiers. Had the operation succeeded, Hamas would have claimed responsibility, he said. But Hamas has not been stopping others from attacking Israel because of a change in its strategy. Nor has the movement decided to abandon violence and join the peace process. Hamas is interested in maintaining the undeclared truce with Israel because it needs time to rebuild its infrastructure, which was severely damaged during Operation Cast Lead earlier this year. Hamas is also well aware that the Palestinian public, which paid a very heavy price during the war, is not prepared for another round of violence - at least not now. Scores of Palestinian families who lost their homes during the IDF offensive are still living in tents and public buildings, or with relatives and friends. Because of the ongoing blockade and the international sanctions, Hamas has not been able to do any major reconstruction in the Gaza Strip. Another war will only increase bitterness among the Palestinians, who are likely to turn their anger not only against Israel, but also against Hamas. Violence and anarchy in the Gaza Strip will only undermine the Hamas regime and loosen its grip on the area. Hamas is prepared to do almost everything to retain its control over the Gaza Strip - even if that requires abiding by an unofficial cease-fire with Israel and preventing others from violating it. Hamas is even prepared to resume "unity" talks with its arch-rivals in Fatah, which is why the movement's leader, Khaled Mashaal, is on his way to Cairo.