Jerusalem ? A beleaguered Yasser Arafat vowed in a televised speech Wednesday to unleash his security services to prevent terrorist attacks, hours after the Islamic militant group Hamas claimed responsibility for a suicide bombing that killed 15 Israelis.

“I gave my orders and directions to all the Palestinian security forces to confront and prevent all terror attacks against Israeli civilians from any Palestinian side or parties,” Arafat said on Palestinian TV.

President Bush called Arafat’s statement against terrorism an “incredibly positive sign,” and he urged Israel to consider the consequences of its response to the suicide attack.

“You’ve got to want peace to achieve peace,” Bush said in Washington, just before meeting with Jordan’s King Abdullah II.

Meanwhile, Israeli Prime Minister Ariel Sharon returned home from talks in Washington to determine Israel’s response. Early today, the Israeli Security Cabinet “authorized the prime minister and defense minister to decide on actions against terror targets.” No details were given of the decision, which came after Sharon’s Security Council met.

Palestinian officials, speaking on condition of anonymity, said they expected Israel to strike at the Gaza Strip, home base of Hamas, which claimed responsibility for Tuesday’s bombing and scores of other attacks during the past 19 months of fighting.

Sheik Ahmed Yassin, the Hamas spiritual leader, told The Associated Press Wednesday his group would continue attacks against Israel. “Israel’s action will not go unpunished. They have harmed civilians, and so their civilians will be harmed,” he said.

Defense Ministry spokesman Yarden Vatikay declined to comment on the possibility of an incursion into Gaza.

“Where there are terrorists, we will act and are acting now,” he said.