Hamas's victory in the Palestinian parliamentary elections in January 2006 and its violent takeover of the Gaza Strip in June were very bad news for those who believe in Israeli-Palestinian peace. But as Israel and the Palestine Liberation Organization prepare to launch formal negotiations on final status -- for the first time in seven years -- Israel should seek to reach a cease-fire with Hamas as soon as possible.

This is not an easy position for an Israeli to take. Hamas is a religiously fanatical organization that has used the worst kind of terrorist violence against Israelis. That Hamas won parliamentary elections does not automatically render it politically legitimate. Democracy is about more than winning elections, and Hamas's violent takeover of the Gaza Strip was a flagrant demonstration of its readiness to defy democratic principles.

But politics is full of paradoxes, and Hamas's takeover of Gaza did create an opportunity. Put schematically, as Gaza fell to the "bad guys," the West Bank was reclaimed by the "good guys," who quickly distanced themselves from Hamas and set up their own pragmatic (in some ways, liberal) government. For Israeli Prime Minister Ehud Olmert, Palestinian President Mahmoud Abbas could now be recast as the politically sanitized partner that Olmert had insisted he so dearly wanted.

Yet even as the new status quo has allowed Olmert and Abbas to embark on a serious process, it also presents both leaders with unprecedented challenges. Hamas's control of Gaza gives it a political and geographical platform from which to disturb -- even to spoil -- any peace talks. Already Hamas permits the constant firing of Qassam rockets into Israel, and it threatens to carry out suicide bombings inside Israel. If it continues to be sidelined, Hamas will probably try to thwart the upcoming meeting in Annapolis, and the process the participants hope to ignite, by escalating the violence to such a degree that the parties will find it difficult even to meet, let alone negotiate peace.

In other words, precisely because Israel and the PLO are ready to sit down and talk, Hamas cannot be ignored. Unfortunately, a broad coalition has formed of those who believe that it not only can be ignored but should be. This coalition includes the majority of Arab states, which support an embargo on Gaza for fear that Hamas's political success there would strengthen radical Islamism in their own countries, as well as the United States, the European Union, and the Palestinian leadership in Ramallah, which is determined to force Hamas to admit failure and give up power.

Against such a broad coalition, it is hard for an Israeli to talk about engaging Hamas, let alone about a cease-fire. But unlike many others, Israel cannot afford to pretend that Hamas does not exist. Hamas is our next-door neighbor, not that of Washington or Brussels or (with all due respect to Egypt's sensitivity to the dangers of fundamentalist fervor) Cairo. We are responsible for the lives and security of our citizens, whether they live within range of the Qassam rockets or in the bustling centers of Tel Aviv and Jerusalem.

Israel also continues to share residual responsibility for the welfare of the 1.4 million Palestinian residents of the Gaza Strip, which Israel occupied for nearly 40 years. The fact, moreover, that Israel continues to exercise control over all but one of Gaza's entry and exit points, as well as over its airspace and sea territory, places additional responsibilities on it.

Given that the current policy of containment has not quelled the violence across its border, Israel should opt for another way. The only option that I see serving the cause of peace is to enter into a dialogue with Hamas through a third party in order to reach a cease-fire. Such an agreement would include the total cessation of mutual violence; arrangements at the border to allow goods and services to pass in and out of the Gaza Strip; the release of Palestinian prisoners in exchange for the release of Gilad Shalit, the Israeli soldier abducted in June 2006; and a commitment by Hamas to prevent all attempts to undermine next week's meeting in Annapolis and the resulting process.

The prospects for making progress on peace will be greater if we establish peace on the ground here and now.