The bomber was a 28-year-old Palestinian named Mousa Abdel-Qader Ghneimat, who worked as a waiter in a Tel Aviv suburb. An anonymous caller to police claimed credit for the bombing on behalf of the Islamic movement Hamas. Netanyahu blamed Yasir Arafat. He charged that Arafat’s Palestinian Authority gave ““the green light’’ to terrorists earlier this month, when it released about 25 Hamas activists from prison, including a prominent leader named Ibrahim Makadmeh.

Arafat condemned the bombing, and Makadmeh was quickly rearrested. But Palestinian spokesmen charged that Netanyahu himself ratcheted up tensions by deciding to build 6,500 Jewish housing units at Har Homa, on the outskirts of Arab East Jerusalem. ““The terror of bulldozers led to the terror of explosives,’’ said Ahmed Tibi, an aide to Arafat. When a television reporter asked Netanyahu whether Har Homa had provoked Arab violence, he replied indignantly: ““I find this line of questioning not only obnoxious but immoral. What you’re saying is that something justifies terrorism, [that] it is permissible to murder women and children.''

Certainly Arafat wasn’t saying that. Last year, after a series of suicide bombings killed 62 people in Israel, he cracked down on Hamas. Several hundred militants were jailed, and Arafat’s police were so hard-nosed that human-rights groups regularly accused them of torturing suspected terrorists. Now the good will generated in Israel by the crackdown seems to have been used up. Arabs ri- oted in Hebron, and Israel closed its borders to Palestinians. Netanyahu warned: ““The peace process is threatened by a mentality that says if we have a disagreement with someone, we can blow them up.''

Last year, when the peace process faced a similar stalemate, Bill Clinton summoned the principals, along with Jordan’s King Hussein, to an emergency summit at the White House. From that meeting came the marathon negotiations that eventually led to an Israeli withdrawal from most of Hebron. Afterward, U.S. officials said they would step back and let the two sides continue on their own. Now, only two months later, it may be time for the Americans to step up again.