Israeli tanks and troops are carrying out more military operations in West Bank cities and villages - following a second Palestinian suicide bombing in two days in Jerusalem. Israeli armored vehicles rolled into the West Bank cities of Bethlehem and Tulkarm early Thursday.

The action follows similar troop movements a few hours earlier when Israeli forces carried out brief incursions into Ramallah - home to Palestinian leader Yasser Arafat. Witnesses said Israeli forces also entered the Bitunyia suburb, west of the city.

Late Wednesday, Israeli helicopters fired missiles at three metal factories in the Gaza Strip. Palestinian doctors say the attacks injured 13 people. Israeli forces moved into the cities of Jenin, Qalqilya, and Hebron earlier in the week.

The incursions into Palestinian controlled territory followed the announcement of a major policy shift by Israel. The government announced it would re-take and hold certain areas until suicide attacks against civilians were stopped.

The policy shift followed an especially brutal attack on a bus in southern Jerusalem early Tuesday. That blast killed 19 and wounded 50 more.

The next evening, six more Israelis died and about 35 were wounded in a bomb attack at a bus stop in the French Hill part of Jerusalem. Palestinian leader Yasser Arafat issued a statement Thursday calling for a complete halt to all attacks against Israeli civilians.

He said all shootings and bombings must be completely stopped or, he warned, the result might be the full occupation of Palestinian lands.

The statement was distributed by the official Palestinian news agency Wafa. The Al Aqsa Martyrs Brigade, which is an off-shoot of a group affiliated with Yasser Arafat's Fatah movement, claimed responsibility for Wednesday's suicide bombing.

The Palestinian militant group Hamas, which has claimed responsibility for numerous attacks including Tuesday's bus bombing, said it would not stop the bombing.

News agencies quoted Hamas spokesman Ismail Abu Shanab in the Gaza Strip as saying, "If we have an effective weapon in our hands and the whole world is trying to take it off us, this kind of reaction shows it to be the most effective way."