RAMALLAH, West Bank - Saying Israel is in a war for survival, Prime Minister Ariel Sharon vowed to smash Palestinian militants in an uncompromising offensive, as he addressed a nation rattled by five suicide bombings in five days, including back-to-back attacks yesterday that killed 14 Israelis.

In an expansion of Israel's "Operation Protective Wall," more than 100 Israeli tanks entered the West Bank town of Qalqiliya late yesterday, Palestinian witnesses said. Electricity was cut off and exchanges of fire could be heard. Armored vehicles also amassed near biblical Bethlehem.

In Ramallah, under Israeli control since Friday, dozens of European peace activists, their arms raised and holding white flags, marched past bewildered Israeli soldiers into Yasser Arafat's office to protest the confinement of the Palestinian leader by Israel. The protesters said they would stay with Arafat, who has accused Israel of trying to kill him, acting as human shields.

Earlier in the day, Israeli forces surrounding the building exchanged fire with Arafat's guards, and Palestinian officials said Arafat was just a few yards from the fighting. Several guards were wounded, two of them seriously. At least 15 Palestinians and two Israeli soldiers have been killed in Ramallah since Friday.

The Israeli army spokesman, Brig. Gen. Ron Kitrey, acknowledged that Arafat was at risk, even if he was not a target.

Addressing the nation in a five-minute televised speech, Sharon said Israel is fighting a "war over our home" and branded Arafat an enemy of the Jewish state and the "entire free world," as well as a danger to the Middle East.

"We must fight against this terrorism, fight with no compromise, pull up these wild plants by the roots, smash their infrastructure, because there is no compromise with terrorism," Sharon said, adding that only then a cease-fire would be possible.

Palestinian Cabinet Minister Saeb Erekat said the speech was "void of substance, void of hope, void of realism." Erekat said Sharon "slammed the door tonight in the face of all of those who are trying to de-escalate."

The Cabinet met yesterday to review plans for the next stage of the offensive, for which 20,000 reserve soldiers were mobilized, at a cost of millions of dollars a month.

Still, some expressed unease over what they called the campaign's vague goals. The Tel Aviv Stock Exchange dropped by 5 percent points yesterday, and the dollar rose 2.8 percent against the shekel.

Some newspaper commentaries said the military campaign was mainly driven by Sharon's need to settle a personal score with Arafat, who in 1982 was besieged by Sharon's forces in Beirut, but was able to leave Lebanon with thousands of fighters.

"This explains Sharon's tremendous urge to humiliate Arafat," Nahum Barnea wrote in the Yediot Ahronot daily.

In the first of yesterday's two suicide blasts, a Palestinian from the Islamic militant group Hamas blew himself up in a restaurant, killing himself and 14 diners, and wounding more than 40.

The blast tore away much of the roof and shattered tables and windows. Twisted piles of metal covered the floor. "Even the moderately injured were on fire," said a witness, Shimon Sabag, who helped administer first aid.

Two hours later, a suicide bomber walked into a paramedics' dispatch station in the Jewish settlement of Efrat in the West Bank and detonated his explosives.