JERUSALEM — Israel scored a major hit against an arch foe by killing Hamas founder Sheik Ahmed Yassin — but the satisfaction may be short-lived.

The missile strike Monday boosted the Islamic militant group at the expense of Palestinian moderates, dealt a possibly fatal blow to U.S.-led peace efforts and drew worldwide condemnation. It is bound to trigger revenge bombings and could draw militants worldwide into the conflict with Israel.

Israeli leaders acknowledged they expect new Hamas attacks on Israeli civilians. However, they said they had no choice but to act against Yassin, portraying him as the "mastermind of Palestinian terror" who personally signed off on every Hamas suicide bombing.

But why target Yassin now?

Israel could have easily killed Yassin in the past. The preacher never went into hiding in over three years of Israeli-Palestinian fighting, instead shuttling between his home in the rundown Sabra neighborhood of Gaza City and a nearby mosque where he prayed five times daily.

Prime Minister Ariel Sharon is under growing pressure at home to score a decisive victory against Hamas ahead of a possible withdrawal from the Gaza Strip. The proposed pullback — Sharon said last month he may leave virtually all of Gaza if peace efforts remain stalled — has many opponents in Israel.

Israeli generals, expressing concern Israel will be seen as fleeing Gaza, have advocated harsh strikes against Hamas.

They said they do not want to see a rerun of Israel's hasty retreat from Lebanon in May 2000, which was claimed as a victory by Lebanese guerrillas and was seen as inspiring the outbreak of the Palestinian uprising months later.

Hamas already has bragged it is chasing Israel out of Gaza, and has accelerated attacks, including a deadly double bombing at an Israeli port last week.

In this climate of one-upmanship, Yassin was a tempting target.

The bearded Hamas leader with the frail voice and white headscarf was a symbol of the Palestinian uprising against Israeli occupation, and relentlessly railed against Israel from pulpits and in TV interviews.

However, Israeli opposition leaders warned Monday that the assassination could draw Muslim militants worldwide into a confrontation with Israel.

Yassin was revered as an Islamic leader, not only as the head of the second-largest political movement in the West Bank and Gaza.

Ran Cohen, a legislator from the opposition Yahad Party, said Defense Minister Shaul Mofaz "opened a front against Islam, not just against the Palestinians."