Israeli armored vehicles entered the West Bank town of Ramallah early Thursday and surrounded the office of Palestinian leader Yasser Arafat, witnesses said.
Israeli military sources, speaking on condition of anonymity, would say only that a military operation was in progress there.
At least two tanks and three armored personnel carriers took up position around the Palestinian leader's headquarters and sounds of gunfire could be heard.
It was not immediately clear whether the Israelis planned to renew their siege on Arafat's office or even try to expel him.
The incursion followed a Palestinian attack on a bus in Israel's north on Wednesday in which 17 Israelis were killed. A Palestinian drove a car with about 42 pounds of explosives next to a bus and exploded the bomb, hurling the bus into the air and setting it on fire.
At the beginning of a large-scale invasion of the West Bank on March 29, following an earlier string of Palestinian suicide bombings, Israeli tanks crashed through the outer wall of the large compound and surrounded Arafat's office, trapping the Palestinian leader inside for 34 days.
There has been speculation in Israeli media that another major Palestinian terror attack would bring the Israeli government to a decision to expel Arafat.
Israeli officials blamed Arafat for the bombing, charging that he has done nothing to stop the attacks. Some Cabinet ministers called for Arafat's expulsion.
The radical Islamic Jihad group claimed responsibility for the attack and said the bomber came from Jenin, a West Bank town near the scene of the bombing.
Israeli tanks entered Jenin a few hours later, and Israeli helicopter gunships fired missiles at the town.
Israeli officials blamed Arafat for the bombing, charging that he has done nothing to stop the attacks. Some Cabinet ministers called for Arafat's expulsion.
Prime Minister Ariel Sharon delayed his departure for the United States, set for later Thursday, because of the bomb attack. He is now planning to leave Saturday night, his office said, and is to meet US President George W. Bush in Washington on Monday.
(China Daily June 6, 2002)
