Israeli tanks encircled Palestinian leader Yasser Arafat's badly damaged headquarters and barricaded the front gate with debris as the army seized control of Ramallah yesterday in its widening West Bank operation.

　　In the southern Gaza Strip, Israeli helicopters fired missiles at two cars, killing six Palestinians and injuring five, Palestinians said. Four of the dead belonged to the militantsgroupsHamas, the movement said.

　　The Israeli military said it targeted and killed Yasser Rizik, a "senior Hamas activist" who was behind a January attack that killed four Israeli soldiers.

　　Also in Gaza, Palestinian police surrounded the house of Hamas spiritual leader Sheik Ahmed Yassin, and Palestinian authorities said he was under house arrest, said The Associated Press. About 40 Hamas sup-porters threw stones and bottles at the police, who firedsintosthe air to quell the crowd.

　　The latest turbulence came as both sides awaited an address by U.S. President George W. Bush, who was expected to propose a fresh start for peacemaking and offer guidelines for a future Palestinian state. Bush put off the speech last week because of the escalating violence, which included three major Palestinian attacks that left more than 30 Israeli civilians dead, and prompted the Israeli invasion.

　　In Washington, there's been widespread speculation that Bush's plan will call for a provisional Palestinian state. The details are not known, though the idea has so far received a cool reception in the Mideast.

　　Israeli Prime Ministers Ariel Sharon said last week that the time was not "ripe" for any sort of Palestinian state.

　　Palestinian Information Minister Yasser Abed Rabbo said that "any initiative or any idea is worthless today, because what's important is the Israeli invasion."

　　Rabbo said it was "the responsibility of the American administration to pressure the Israelis to pull back before talking about initiatives and peace talks."

　　In Ramallah, the Palestinian political headquarters in the West Bank, Israeli soldiers atop armored personnel carriers flashed V-for-victory signs as dozens of tanks and armored personnel carriers rolledsintosthe city under the cover of two helicopters.The troops took up positions around Arafat's offices,swheresa bulldozer quickly began fortifying barriers at the front gate. More than 20 tanks were parked on the street that surround Arafat's compound yesterday afternoon.

　　Israel forces have besieged Arafat's compound on and off since last December, and yesterday's action marked the third time this month when troops have surrounded his offices, which now consist of many battered and scorched buildings that cover a full city block.