Israeli troops enter Nablus in retaliation for bus bombing

? Israeli troops and tanks moved into the West Bank towns of Nablus and Jenin early today, searching for Palestinian militants in the wake of a devastating suicide bombing earlier in the week, police and Palestinian officials said.

Shots rang out in Jenin after some 20 tanks, personnel carriers and other vehicles entered, witnesses said, but there were no immediate reports of casualties in either town. A curfew was imposed in central Nablus after more than 30 vehicles — mostly trucks and a few tanks — entered the town.

Troops were also searching for bomb laboratories, an Israeli military source said on condition of anonymity. No arrests were made in the latest raids, though on Wednesday night six wanted Palestinians were arrested in the area of Jenin, the source said.

Israeli Prime Minister Ariel Sharon has approved a series of “pinpoint” military strikes in response to a suicide bombing that killed 20 and injured more than 100 in Jerusalem on Tuesday.

In response, Palestinian Prime Minister Mahmoud Abbas on Wednesday ordered the arrests of suspects directly involved in Hamas bombing, but said he would not clamp down on militant groups without Arafat’s backing, Palestinian Information Minister Nabil Amr said.

A meeting between Abbas, Arafat and other top Palestinians to discuss how best to respond to the suicide attack stretched into the early hours today. Participants said the talks were tense and erupted in yelling.

Five Americans were among those killed in Tuesday’s attack on a Jerusalem bus, the U.S. Embassy said. The bus bombing Tuesday was the deadliest attack since President Bush unveiled his “road map” peace plan in May, and the tragedy was magnified by the fact that six children, ranging in age from 3 months to 15 years, were among the dead.

On Wednesday, Secretary of State Colin Powell called Abbas and told him he expected “immediate measures to stop the deterioration,” Amr said. It was not clear whether Powell issued an ultimatum.

The Jerusalem bombing came in revenge for the killing last week of an Islamic Jihad leader, Mohammed Sidr, in an army raid in the West Bank city of Hebron. The bomber was a 29-year-old mosque preacher from Hamas and a friend of Sidr’s.

Israeli army tanks line up in the outskirts of the West Bank town of Ramallah. Israeli Prime Minister Ariel Sharon approved a series of pinpointed military strikes that began early today after a suicide bomber killed 20 people and injured scores in downtown Jerusalem on Tuesday.