JERUSALEM, Aug. 12 (JTA) — The suicide bombings that hit Israel this week shattered the relative calm that had taken hold in Israel and the West Bank this summer. How they will affect the cease-fire declared by Palestinian terrorist groups and implementation of the "road map" peace plan is anybody´s guess. At the least, they certainly indicate differing interpretations of the concept "cease-fire." With the truce now six weeks old, Israel expects the Palestinians not just to halt all terror attacks but to crack down on terrorist groups, which the Palestinians are obligated to do under the road map. "If the Palestinians do not do what they ought to do, it will not be possible to make progress in the process, and at the end of the day the Palestinians might not achieve what they want to achieve," Israeli Prime Minister Ariel Sharon warned after the attacks, which killed one Israeli man in the city of Rosh Ha´ayin and a teenager near the West Bank settlement of Ariel. But Elias Zananiri, a spokesman for the Palestinian Authority´s security chief, Mohammed Dahlan, said the terrorist attacks emanated from areas that still are under Israeli security control. "The Palestinian security forces in the West Bank do not have the ability to do what they are requested to do," he said. The Al-Aksa Brigade of the Palestinians´ mainstream Fatah movement claimed responsibility for the Rosh Ha´ayin attack. The Islamic fundamentalist group Hamas claimed responsibility for the Ariel attack. In response, Israel suspended the release of 77 Palestinian prisoners who were due to be freed Tuesday. The attacks, which are not believed to be linked, represent the most blatant violation of the cease-fire the terrorist groups declared six weeks ago. Seven Israelis and 12 Palestinians — excluding suicide bombers — have been killed since the cease-fire took effect on June 29. The Palestinian Authority condemned the attacks, but P.A. Prime Minister Mahmoud Abbas said they were provoked by recent Israeli anti-terror raids in the West Bank. Abbas said he did not consider Tuesday´s bombings a violation of the cease-fire, according to an Associated Press report that cited a Qatari news agency. Hamas appears to feel the same way. Mahmoud a-Zahar, one of the leaders of Hamas in Gaza, said the organization was still observing the cease-fire but that "the operations are a natural reaction to the Israeli violations of the cease-fire." A-Zahar seemed to be referring, in part, to an Israeli operation in Nablus last Friday in which one Israeli soldier and four Palestinians — including two members of Hamas — were killed. But more broadly, Israel has continued certain anti-terror operations during the cease-fire, arresting some 200 Palestinians even as it released more than 300, Palestinians say. Israel views the cease-fire as an internal Palestinian affair that does not bind Israel. It says the terrorist groups are using the cease-fire to rearm, and demands that the Palestinian Authority fulfill its commitment to dismantle the groups. Until the Palestinian Authority begins to act, Israeli officials said, Israel will continue its anti-terror operations, though they have been toned down significantly since the cease-fire was declared. Abbas has said he will not confront the terrorists for fear of igniting a Palestinian civil war. Despite the cease-fire, Israeli security sources say gangs of terrorists have received money from Hezbollah and Iran to continue terrorist attacks. Israeli forces are believed to have foiled at least 10 suicide-bombing missions in the past few weeks. American officials condemned Tuesday´s attacks. Secretary of State Colin Powell said peace is impossible as long as "people continue to participate in terrorist activities, and we see the response to terrorist activities, which are necessary for self-defense." Powell made his comments at a State Department gathering of Israeli and Arab children from the Seeds for Peace conflict resolution camp. Powell also emphasized that the United States would continue to work with its partners in the "Quartet" — the United Nations, Russia and the European Union — to implement the road map. For Israeli officials, one thing remained clear: The cease-fire had not removed the need to fight against terrorism. "This is not the first terrorist attack during the hudna, and we believe it will not be the last," Israel´s police chief, Shlomo Aharonishky, said of the Rosh Ha´ayin attack, using the Arabic term for a cease-fire. In Islamic tradition, a hudna implies a temporary truce during which forces are rebuilt for future rounds of fighting.