MEGIDDO, Israel - Israeli tanks re-entered the West Bank city of Ramallah early this morning and surrounded the office of Palestinian leader Yasser Arafat, hours after a Palestinian suicide bomber detonated a car packed with explosives alongside a moving Israeli bus, incinerating the bus and killing 17 passengers on board.
Israeli troops and armored vehicles blew up offices of the Palestinian intelligence service, about 200 feet from Arafat's quarters, witnesses said. Palestinian officials said Arafat was unharmed.
The Israelis left the compound early this morning, about six hours after they entered.
The Israeli military said it acted amid "a wave of Palestinian terrorism sweeping the state of Israel," including yesterday's bus attack.
The latest incursion into Ramallah came exactly five weeks after U.S. intervention helped lift a 34-day siege of Arafat's headquarters and amid talk of renewed action against the Palestinian leader.
Earlier, tanks and armored personnel carriers broke a huge hole in the outside wall and sent bulldozers inside to knock down structures.
The action signaled that Prime Minister Ariel Sharon held Arafat personally responsible for failing to halt militants' attacks against Israelis. The bombing of the bus was a seemingly well-planned event that worked with deadly precision, heralding what Israeli officials warned was a shift in tactics by militant groups to kill more Israelis with each bombing.
The bomber used a stolen Renault and, traveling at about 50 mph, waited until he was alongside the fuel tank of the bus before setting off the explosives. The bus burst into flames, overturned twice and blew up.
Survivors climbed out of windows and then helplessly watched trapped passengers screaming for help. One couple embraced before they were swallowed by flames that left the bus a skeleton of charred metal.
At least 40 people were injured, seven seriously. Of the dead, 13 were soldiers, most returning to their bases in northern Israel from leave in Tel Aviv and surrounding suburbs.
Within hours of the blast, Israeli helicopters fired missiles into the West Bank city of Jenin, the home of Hamza Samudi, 16, identified by the extremist organization Islamic Jihad as the bomber. Later, two dozen tanks took over the streets and soldiers imposed a curfew.
In statements to television stations in Lebanon, Islamic Jihad said it timed yesterday's bombing to the 35th anniversary of the start of the 1967 Arab-Israeli War, when Israel captured the West Bank and Gaza Strip.
The Palestinian Authority condemned the bombing in a statement that said it had no advance knowledge of the attack. Palestinian officials said they were under orders to arrest members of Islamic Jihad.
In Washington, the White House condemned the attack and said it raised questions about Arafat's role in the Middle East peace process.
"In the president's eyes, Yasser Arafat has never played a role of someone who can be trusted or effective," press secretary Ari Fleischer said.
Liron Ben-Or, a 20-year-old army paratrooper, was dozing when the bomb went off. He awoke in a hospital bed in nearby Afula, his left eye and cheek covered with patches and dried blood caked to his face.
He summed up the uncertainty felt by many Israelis in a conflict in which cities and highways are the front lines. "In this situation, you don't know whether to be afraid or not," Ben-Or said.
Israeli cabinet ministers renewed their debate about what kind of action the military should take, and apparently authorized the army's return to Ramallah.
"There is no doubt that Israel cannot sit quietly and refrain from considering an operation, a very, very significant response, in order to prevent disasters of this type," Education Minister Limor Livnat said after a meeting of Sharon's security cabinet
For months, Sharon has insisted that negotiations with the Palestinian Authority would be impossible as long as Arafat remained at its head. On Tuesday, CIA Director George J. Tenet met with Arafat in an effort to restructure his security forces and restore his credibility with the Bush administration and Sharon.
Israeli police and army commanders have warned of a large-scale attack for weeksLast month, an attempt to blow up a gas storage yard by remote control failed. And officials said a bomber who struck a hotel in Netanya in March apparently intended to release cyanide gas, a plan that went awry.
In yesterday's attack, the bomber used a car as a weapon. Police estimated the explosives weighed up to 50 pounds, five times more than the amount suicide bombers can conceal in a belt or vest.
Authorities said the car used had been stolen several months ago in the Israeli town of Lod, and that the license plates were stolen from a second car near Tel Aviv. They said the car was driven to the West Bank and then driven into Israel yesterday morning, probably through an army checkpoint.