Thursday's attack, in which eight Israelis were killed and some 30 wounded, was one of the worst terror attacks Israel has experienced in recent years.

Israeli defense sources said the cell, belonging to the Popular Resistance Committees, left the Gaza Strip through the tunnels and entered Israel from Sinai to carry out a suicide attack combined with an abduction. Seven of the terrorists who carried out the attack were killed by the IDF and special police forces, as well as by fire from the Egyptian army.

In retaliation the IDF bombed a house in Rafah on the Egyptian border, killing the Popular Resistance Committees' military commander, Abu Awad a-Naireb and two of his deputies. Two other activists of the organization and a Palestinian boy were killed.

The house was apparently a headquarters for the Committees' leaders.

Thursday afternoon the Popular Resistance Committees, a group that quit Fatah in 2001 and was partner to abducting Gilad Shalit in June 2006, said they no longer recognize the cease fire with Israel. Shortly afterward two rockets were fired toward Ashkelon. Nobody was hurt.

Egypt's defense forces said they were combing the area on the Egyptian side of the border to make sure there were no more terrorists at large.

The attack took place despite a specific warning about the intention of Palestinian terror groups to carry out an attack or try to abduct a soldier in the south.

Hamas refrained from firing rockets at Israel yesterday. Its conduct will determine whether or not there is an escalation. The group's military arm yesterday issued a statement saying it will react with force to any Israeli aggression in Gaza. But Hamas, especially its political leaders in Gaza, have no interest in escalating the fighting with Israel. It is not clear at all if Hamas even knew of the Resistance Committees' intention to carry out a terror attack on two buses and private cars filled with civilians - something that would be sure to lead to an Israeli retaliation.

On the other hand, Hamas has close ties with the Committees, including military cooperation, from the day Jamal Abu Smahadna founded the Committees and joined Hamas. For example, after Smahadna was killed in the beginning of June 2006 in an Israeli bombardment, Hamas, the Resistance Committees and the Islamic Army carried out a joint attack near Kerem Shalom, in which Gilad Shalit was abducted. At the end of a financial negotiation among the three organizations it was decided Hamas would keep Shalit.

Thursday's attack required the cooperation of the Bedouin in Sinai and groups identified with World Jihad acting in the peninsula. The attack itself consisted of at least three different sites, a large number of terrorists in the field and coordination with observation and intelligence teams.

Presumably, the chaos in Sinai since the revolution in Egypt and the ongoing arms and fugitives' smuggling from Sinai to Gaza and in the opposite direction, made it easier to carry out the attacks than it would have been before the revolution.

This is the most problematic issue for Israel - the security vacuum in Sinai, as Defense Minister Ehud Barak called it. What was Israel's quietest border for many years has , over the past few months, turned into the deadliest one.

Ironically, Israel's warnings of the implications of the Egyptian regime's weakening following the revolution, warnings that were roundly criticized in the world, turned out to be correct and even relatively optimistic. About six months after Hosni Mubrak was deposed, Sinai constitutes a shelter for World Jihad activists and is no longer an Israeli tourists' paradise. The implications of the new Egyptian "democracy" are regrettably well felt on the Israeli side - whether in the form of yesterday's attacks, due to the chaos in Sinai or the unending chase after fake spies (al Ahram reported yesterday that the last Israeli "spy" caught in Egypt, Ophir Harari, "planned to spread poison that will damage the fertility of the men and women in Egypt." )

It should be noted that Cairo is making considerable efforts to reinstate order in Sinai. Since it sent 1,000 soldiers accompanied by tanks and armored vehicles about a week ago, the Egyptian army has exposed a plant for producing weapons in the El Arish area and several arms smugglers have been killed.

In this sense Israel has no choice but to continue and rely to a large extent on the Egyptian army's activity to quash Islamic terror in Sinai. But reinforcing the forces is a drop in the sea in n area more than twice as large as Israel. As long as completion of the border fence between Egypt and Israel drags on, another attack like yesterday's is only a matter of time.