ERUSALEM - Israeli helicopter gunships and warplanes destroyed Palestinian Authority buildings and equipment in Gaza and Jenin yesterday even as Palestinian leader Yasser Arafat scrambled to demonstrate that he was trying to halt suicide bombings and other violence against Israel after horrific attacks last weekend.
Early this morning, Israel launched incursions into the cities of Ramallah and Nablus on the West Bank and began tearing up portions of the landing strip at Gaza International Airport to prevent its use.
And after a prolonged session, the Israeli Cabinet formally declared that the Palestinian Authority was ''an entity supporting terrorism,'' a decision that a top government spokesman said justified military, political, and economic sanctions.
Israeli Prime Minister Ariel Sharon, in a fiery, nationally televised speech yesterday evening hours after he returned from a Washington meeting with President Bush, said Arafat was entirely to blame for the bombings that killed 27 mostly young Israelis at a Jerusalem mall Saturday night and on a Haifa bus Sunday. He warned that ''those who rise up to kill us are responsible for their own destruction.''
Sharon invoked Bush's often-stated principle that those who harbor terrorists bear responsibility for terrorism, and said that Arafat and the Palestinian Authority ''have allowed the terrorist organizations to act, and have given them support and resources.''
He said Israel would act ''with all our force, all our means, and new means'' to pursue those responsible for terror attacks, ''and they will pay the price.''
Arafat, who was in Ramallah at the time of the missile strikes on Gaza, told Abu Dhabi Television, ''They hit my headquarters, they hit my house - the bombings are a humiliation to the Palestinian people.''
Other Palestinian leaders accused Sharon of slandering their chief and preparing for massive attacks. They appealed to the United States and the international community to stay Sharon's hand, and said they would take their case to the United Nations, the Arab League, and Muslim organizations.
Bush administration spokesmen in Washington made clear that the United States had no intention of asking Israel to restrain itself, as it had after some previous suicide bombings. The president, White House spokesman Ari Fleischer said, ''believes Israel has a right to defend herself.''
Israeli airstrikes began just before dusk yesterday, when an estimated nine rockets launched from helicopter gunships struck the Palestinian Authority's Mediterranean seaside headquarters in Gaza City. The heliport and two helicopters that gave Arafat access to the West Bank and the outside world were wrecked. The barracks of Force 17, Arafat's personal guard, were engulfed in flames, and a thick plume of black smoke drifted across the city. No information was immediately available on the extent of damage to Arafat's house.
Initial estimates were that 17 people were injured, and Voice of Palestine radio said two were killed.
After the attack, Voice of Palestine broadcast a song containing the lyric, ''We love you, Abu Ammar, all the people love you, Abu Ammar, you are our leader.'' Abu Ammar is Arafat's nom de guerre.
In Jenin, a city in the north of the West Bank from which numerous suicide bombers have been dispatched to Israel, the Palestinian Authority police headquarters was destroyed. It had been damaged in a previous Israeli retaliation strike.
In Bethlehem, one man was reported killed in a large explosion, but Israeli sources said the blast was not related to any Israeli activities.
Before the Israeli airstrikes were launched, the Palestinian Authority placed Sheik Ahmed Yassin, the founder and spiritual leader of the extremist Islamic group Hamas, under house arrest, arrested two other leaders of the organization, and issued a summons for Abdul Aziz al-Rantisi, Hamas's cofounder and chief spokesman. Hamas, which took responsibility for the weekend terror attacks, is classified as a terrorist group by the US State Department.
More than 150 militants were arrested overnight Sunday and yesterday in the West Bank and Gaza, Palestinian officials said, sparking protests in some places and a rebellion in a Bethlehem refugee camp that forced Palestinian Authority police to back off.
But Arafat's declaration of a state of emergency on Sunday and a Palestinian Authority statement that those responsible for ''killing the civilians in Israel will be brought to trial'' apparently alerted many other extremists, and ''most people ran away,'' said Colonel Abdullah Daoud, the authority's intelligence chief in Bethlehem.
Whether Arafat is willing to lead a genuine crackdown on terrorists or is only making show, and whether he would be able to maintain his position if he did really crack down are open questions.
The Palestinian public is strongly opposed to a crackdown, and Hamas has been gaining popularity at the expense of Arafat's Fatah movement.
Daoud said that when Palestinian policemen entered the Dheishe refugee camp to arrest an activist, ''hundreds of people went out into the streets,'' some firing into the air, and prevented the arrest.
Abdel Majid Atta, a Hamas spokeman in Bethlehem, said yesterday that the organization was told by the regional governor that the Palestinian Authority was going to make arrests, and ''we rejected that.''
''The authority is facing a big danger that it might collapse,'' said Atta, who has been jailed by both the Israelis and the Palestinian Authority in the past. ''The danger comes from Israel. Sharon is crazy. If they arrest us, will the martyrdom be stopped? That is a joke.
''Arafat cannot outlaw Hamas, PFLP, DFLP, and Fatah,'' said Atta, reeling off the acronyms of major militant groups. ''He cannot outlaw the entire Palestinian people.''
Israeli and American officials were highly skeptical of Arafat's putative crackdown. Bush, White House spokesman Fleischer said, ''thinks it very important that Palestinian jails not only have bars on the front, but no longer have revolving doors in the back.''
Israel might outlaw the organizations Atta mentioned and more. Israel's Channel 2 Television reported that the government is considering outlawing those factions plus Force 17 and the Fatah-affiliated Tanzim militia.
Israel has in the past expelled and imprisoned large numbers of Palestinian militants.
Turkey, a majority Muslim nation that is also a NATO member and close ally of Israel, said it would try to bring representatives of the two sides to talks quickly.
Prime Minister Bulent Ecevit spoke to Arafat and was trying to reach Sharon, Reuters reported. Ecevit said ''a meeting has been organized in Norway, and [Arafat] wants it to take place.''
Charles A. Radin can be reached by e-mail at radin@globe.com
