However, both sides indicated they wanted the cease-fire to continue despite the bombings on Tuesday.
Israeli police said they were on nationwide alert Wednesday, setting up roadblocks on key roads and at the entrances to Israeli towns in an attempt to head off any further attacks. Israeli army radio said intelligence sources had warnings of 21 impending attacks — up from seven or eight daily warnings a week ago — but a police spokesman would not say how many warnings had been received.
The blasts, in an Israeli town and at a West Bank bus stop used by Jewish settlers, killed two Israelis and wounded 11. The two attacks were 11 miles apart and occurred within an hour of one another but were not related, police and army officers said.
In response, Israeli Prime Minister Ariel Sharon said, "There can be no peace with terror." He was addressing thousands of visiting students, many from the United States, on Tuesday night.
Sharon said the attacks were the result of a "complete lack of Palestinian action" in dismantling militant groups like Hamas and Islamic Jihad, as required by the current U.S.-backed "road map" peace plan.
"As long as terror continues, as long as the Palestinian Authority does nothing to fulfill its commitments" to disarm militants, he said, "it will be impossible to move forward."
However, Israeli officials refrained from threatening large-scale military retaliation, indicating that they want the relative calm to be restored.
Hamas and a faction loosely linked to Yasser Arafat's Fatah movement each claimed responsibility for one of the attacks.
Hamas said the bus stop bombing, near the Jewish settlement of Ariel, was to avenge the killing of two of its bombmakers in an Israeli army raid Friday, and that the group would now return to observing its three-month truce.
A renegade faction of the Al Aqsa Martyrs' Brigades which opposes the cease-fire claimed responsibility for the attack on the town of Rosh Haayin, east of Tel Aviv, and threatened more attacks "until the occupation is defeated." Fatah itself declared a six-month halt to attacks on June 29.
The army blew up the family home of the Rosh Haayin bomber, 17-year-old Khamis Gerwan, in the Askar refugee camp on the edge of the city of Nablus, obliging its 11 remaining occupants to move in with relatives nearby, camp residents said.
"The demolition of houses of terrorists sends a message to suicide bombers and their partners that anyone that anyone who participated in terrorist activity will pay a price for their actions," an army statement confirming the demolition said.
The military also said it arrested seven wanted militants in and around Nablus.
Tuesday's suicide attacks were the first since July 7, when a bomber killed a woman in an Israeli village. Seven people have been killed on the Israeli side since the unilateral Palestinian truce was declared on June 29. In contrast, 30 Israelis were killed by suicide bombers in the six weeks before the truce.
Fifteen people, including the three bombers, have been killed on the Palestinian side since the truce began.
Palestinian Prime Minister Mahmoud Abbas insisted the Palestinian factions remain committed to their truce. "The escalation of the situation came from the Israeli side," Abbas said in Qatar, before heading to Amman, Jordan, where he met with senior U.S. envoy William Burns on Wednesday.
Sharon also met Burns Tuesday night in Jerusalem, and Israel Radio reported Sharon and Abbas will meet sometime later this week.
Abbas and Burns discussed Tuesday's two Palestinian attacks on Israeli targets as well as implementation of the road map peace plan, Palestinian officials told Haaretz newspaper.
In Washington, Secretary of State Colin Powell said the administration would continue to push for a peace accord, but that it would not succeed unless violence stopped.
"We will never get there so long as people continue to participate in terrorist activities, and we see the response to terrorist activities, which are necessary for self-defense," he said
Both Tuesday's bombers were 17 and lived near each other in Nablus. Police have arrested a man who allegedly drove Gerwan to Rosh Haayin, police commander Amihai Shai told Israel Radio.
Hamas released a letter that it said was written by the second assailant, Islam Qteishat, who blew himself up near Ariel. "Father, don't be sad, lift your head in pride, because your son died a martyr for the sake of God," the letter said.
But the bomber's mother, Yusra, demanded retribution against the militants who sent her son to die — a rare attitude in a society where suicide bombers are usually revered as martyrs. "I'll kill whoever dispatched my son," she screamed, beating her fists against a wall.