Alpher adds: "This was a justified attack, but probably not a wise move. By now, we all know there is no military solution to the conflict. You can get rid of Yassin, but you haven't changed the overall equation.

That has been the case with assassinations before. The terrorist organizations have the capacity to recover. There are plenty of people to fill in and Hamas now has more motivation." He added that he also expects it to lead to heavy casualties as Hamas retaliates.

In Alpher's view, the assassination risks fueling a strong reaction in the wider Arab world that will backfire on Israel. "To the extent that Yassin was seen as an Arab leader by the Arab street, we've crossed a red line here. His status was close to the level of a head of state and the reaction could be quite harsh in Cairo and Amman. We will have to see the extent to which Arab leaders feel the need to punish Israel."

Monday, Lebanon's Hizbullah guerrillas attacked Israeli posts in a disputed border area, drawing air raids, in retaliation for Yassin's killing, the wires reported. Hizbullah's al-Manar TV said Sheikh Ahmed Yassin Brigades, named after the assassinated leader, carried out the attacks on six Israeli positions.

The sheikh's killing drives home the increasingly dangerous disconnect in the way Israelis and Palestinians view each other's tactics in what one Hamas official, Abdel Aziz Rantissi, warns would now be an "all-out war." While the Israeli right defended the assassination as a legitimate step in their struggle against terrorism, Palestinians say it would only unify their splintered society and enlist more willing volunteers for suicide bombings.

Sharon called Yassin the "mastermind of Palestinian terror" and a "mass murderer who is among Israel's greatest enemies," the wires reported. He said Israel will press ahead with its war on terror, signaling more targeted attacks and raids. "The war against terror has not ended and will continue day after day, everywhere," he said.

Israeli Defense Minister Shaul Mofaz said that in the long run, the killing will weaken Hamas, according to The Associated Press. "If we have to balance how many more terrorists Yassin would have sent, how many terror attacks he would have approved, if we weigh this on the scales, we acted rightly," Mr. Mofaz told parliament's Defense and Foreign Affairs Committee, according to a participant at the closed meeting.