There are a few certainties when it comes to the Middle East. One is that Hamas militants will do anything to sabotage Israeli-Palestinian peace efforts. Another is that Israel will retaliate against serious assaults on its people. And a third is that without measurable improvements in the lives of both Israelis and Palestinians, a few spectacular acts of terrorism can derail even the best-intentioned peace talks.

The latest violence, coupled with the Palestinians’ bitter political schism, could doom President Bush’s peace initiative. Giving up is not an option. That would guarantee even more mayhem and perhaps wider war.

If there is any hope of salvaging the effort, the United States, Europe and Arab states must move quickly to arrange a cease-fire between Israel and Hamas and give serious thought to a new strategy for dealing with Gaza.

Arab nations — especially Egypt, Saudi Arabia and Qatar — must help the Palestinian president, Mahmoud Abbas, pressure Hamas into halting rocket attacks against Israel. The United States must persuade Israel that there is no chance of lasting security until Palestinians, both in the West Bank and Gaza, see more benefits from peace than revenge. That means no further expansion of settlements and finding ways for Palestinians to move about and work.

That’s going to require a lot more creativity and hands-on diplomacy than we’ve seen so far. Even in the midst of last week’s bloody fighting, Secretary of State Condoleezza Rice could only manage a two-day stopover in the region. Her only accomplishment: persuading Mr. Abbas to resume peace talks with the Israeli prime minister, Ehud Olmert. Thursday’s killing of eight students at a Jewish seminary in Jerusalem will make the going even tougher.

Mr. Olmert and Mr. Abbas are committed to a two-state solution. But so far there is no real sign of the kind of goal-oriented negotiations that November’s Annapolis peace conference was supposed to initiate.

After Hamas took over Gaza last June, the United States and Israel decided they would boost Mr. Abbas and his moderate Fatah faction while isolating Hamas and Gaza. But Israel didn’t do nearly enough to strengthen Mr. Abbas, and the crushing economic embargo on Gaza only feeds furies there and on the West Bank. It is increasingly apparent that Israel cannot be at war with some Palestinians and try to make peace with the rest.

We are encouraged that Egypt will try to broker an Israeli-Hamas cease-fire. Cairo will need a lot of outside support if it is to halt the killing without enhancing Hamas at Mr. Abbas’s expense. Washington, Europe and the Arab states also need to start thinking hard about what they can do to improve the lives of ordinary Israelis and Palestinians — and give them some faith in the peace effort. Maybe sometime after that, the two sides can talk seriously about a two-state solution.