Hamas threatened "100 unique reprisals" against Israel for killing its leader, Abdel Aziz Rantisi (search), as hundreds of thousands of mourners flooded the streets Sunday in a show of strength and fury.

It wasn't clear if the Islamic militant group was strong enough to carry out large-scale attacks after a sustained two-year Israeli campaign against it. Despite promises of revenge, Hamas still has not struck in the three weeks since Israel assassinated Rantisi's predecessor, Hamas founder Sheik Ahmed Yassin (search).

Hamas chose a replacement for Rantisi on Sunday, but did not disclose his name — a clear sign at least that the group is on the defensive in the face of Israeli attacks ahead of Prime Minister Ariel Sharon's (searchplanned withdrawal from the Gaza Strip.

Sharon on Sunday picked up the support of key Cabinet ministers for his unilateral disengagement plan, including the Gaza withdrawal, assuring him of a Cabinet majority ahead of a hard-fought referendum among the 200,000 members of his Likud Party (search).

Sharon told the Cabinet on Sunday that he would forge ahead with his plan and continue to "hit the terror organizations and their leaders."

Cabinet minister Gideon Ezra said the overall Hamas leader, Damascus-based Khaled Mashaal, was also a target. Rantisi was in charge of the Palestinian areas and reported to Mashaal.

The killing of Rantisi set off demonstrations — some of them violent — across Gaza and the West Bank, as well as in Arab countries.

In the West Bank, Israeli troops shot and critically wounded a 14-year-old Palestinian boy in a clash between stone throwers and soldiers. Late Sunday, police shot two Israeli Arabs in Israel's northern Galilee region, killing one and injuring the other. The police commander said the Arabs opened fire on a border police patrol.

The military reported dozens of minor incidents through the day, most involving Palestinians throwing rocks and firebombs.

An Israeli was moderately injured early Monday when Palestinian militants fired two Qassam rockets at the Jewish settlement of Nitzanit in the northern Gaza Strip, the army said. Five rockets, mortar shells and anti-tank missiles were fired at Gaza settlements overnight but more casualties were not reported, the army said.

A Palestinian who approached a checkpoint near Kesufim in the Gaza Strip overnight also was shot and killed, Palestinian security said Monday. Also in Gaza, the army destroyed a house in an area near Kfar Darom settlement known for exchanges of fire, witnesses said. The army did not immediately comment on either of the Gaza incidents.

In another development, a 24-year-old Palestinian died Sunday of wounds received in clashes during a demonstration against the security barrier Israel is building, hospital officials said. The Israeli military denied it fired live ammunition.

Israel rebuffed international criticism, including by several European countries. It said Rantisi — like Yassin — was targeted because he directed bloody Hamas attacks against Israelis and was planning more.

However, many Palestinians held the United States responsible for Rantisi's death, saying it is giving Israel free rein.

"The Palestinian government considers this Israeli terrorist campaign to be a direct result of American encouragement and the total American bias in favor of the Israeli government," said Palestinian Prime Minister Ahmed Qureia, echoing a widely held sentiment in the West Bank and Gaza.

Palestinian officials are furious with President Bush for sidelining them, endorsing Sharon's unilateral plan and backing Israel's demand to hang on to parts of the West Bank.

Bush's national security adviser, Condoleezza Rice, denied that Bush gave Sharon the go-ahead for the Rantisi killing during their White House meeting last week. She told ABC TV that Israel has the right to defend itself, but that it is "extremely important that Israel take into consideration the consequences of anything that it does."

Mashaal said Sunday that the killing of Rantisi only strengthened his group and boosted support for it. However, a local leader in Gaza, Ismail Hanieh, acknowledged Hamas suffered a momentary setback.

Palestinian officials said they are worried the next target for assassination will be Palestinian leader Yasser Arafat, whom Israel accuses of fomenting terror. The Israeli Cabinet voted last year to "remove" Arafat.

In Sunday's funeral, hundreds of thousands of Palestinians thronged the streets of Gaza City. In addition to Rantisi, two bodyguards were killed when two missiles struck the car they were traveling in.

Hamas supporters chanted "God is great" and "revenge, revenge" and threw flowers at the three bodies as they passed in a procession. They touched Rantisi's exposed face, which was covered with shrapnel wounds.

About 200 armed Hamas militants lined the sides of the road and saluted the bodies as they approached a large blue and green mourning tent set up outside Rantisi's house. Armed men fired into the air and many in the gathered crowd raised their fists in anger.

Hamas posted a statement on its Web site pledging "100 unique reprisals" against Israel. It said it declared a state of emergency in the West Bank and Gaza until revenge was complete.

Hamas leaders have threatened to target Israeli leaders, who are heavily guarded and travel in reinforced vehicles with bodyguards and convoys.

Why Hamas hasn't done so yet is not clear. Israel's campaign against it may have left it weakened, though Israeli terrorism expert Reuven Paz said the killing of Yassin and Rantisi did not reduce the Hamas' ability to carry out attacks. He noted that militant groups are increasingly cooperating for greater effectiveness.

Israel also says its security forces have foiled a dozen planned attacks and a security fence around Gaza has stopped most infiltrations. In one exception, two Palestinians from Gaza hid in a false compartment of a shipping container, made their way to Israel's Ashdod port March 14 and blew themselves up, killing 10 Israelis. That bombing set off the Israeli campaign against the Hamas leadership.

Analysts warn that sooner or later, more Hamas bombers will elude the checks. In more than three years of violence, Hamas has claimed responsibility for dozens of suicide bombings in Israel, killing hundreds.

Hamas has mounted dozens of attacks from the West Bank, but recently the Israeli military claimed it rounded up the entire local Hamas leadership in Nablus, the West Bank's largest city.

Political maneuvering might hold back Hamas. It is in sensitive talks with the Palestinian Authority over possible power-sharing in Gaza after an Israeli withdrawal.

Sharon cleared another obstacle Sunday in getting his unilateral plan approved by his Likud Party, which is to vote on it in a May 2 referendum. Polls show a slim majority in favor of the plan.

Two key Israeli Cabinet ministers, Finance Minister Benjamin Netanyahu and Education Minister Limor Livnat, decided Sunday to back the plan, giving Sharon a Cabinet majority and the support of influential Likud members.