This is a highly significant week for the Middle East. A summit meeting tomorrow in Sharm El-Sheikh may lead to a formal cease-fire agreement between the Palestinians and the Israelis. The summit will follow talks which Condoleezza Rice will have with both sides on her first overseas trip as US secretary of state. These events signify a dramatic return to peacemaking since the eruption of the intifada four years ago. Obviously, an opportunity has now appeared; the question is for how long it will be available.

There is plenty of cause for optimism. Hamas and Islamic Jihad have largely held to an informal cease-fire which the two have agreed on with Palestinian President Mahmoud Abbas who has deployed security forces in Gaza. The combination of these two pushed Prime Minister Ariel Sharon into admitting they had created conditions for a “historic breakthrough” in relations. Sharon has coupled his rare praise with plans to release hundreds of Palestinian prisoners, withdraw from five West Bank cities and end targeted killings of suspected Palestinian activists. In addition, Israel may also open more crossing points for Palestinians.

Problems, however, lurk on the horizon. While the Palestinian Authority wants the release of prisoners, it is asking for thousands, not hundreds. And while Sharon oozed words of praise last week, in his most recent statement it appeared he had Alzheimer’s, accusing the Palestinian leadership of taking insufficient measures against activists and warning that the road map would only be revived “after the Palestinians stop terror activities.”

Nonetheless, Abbas has taken steps to fulfill a number of the Palestinian obligations, which are outlined in the road map. Sharon must now reciprocate. In Sharm El-Sheikh, Abbas will demand a freeze of Israeli construction in occupied Palestinian territory, including Jewish settlements and the West Bank wall. These are some of the main threats to Palestinian hopes for a viable independent state.

Another threat is that Israel is preparing to revive an old law that would allow the seizure of large tracts of Palestinian land in Arab East Jerusalem, the very area where the Palestinians want their capital. The Palestinians want action on all these issues because there is no such thing as a free truce. Abbas needs to see Israeli action on many fronts if he is to consolidate Palestinian support for his leadership and policies. He wants the summit meeting to advance the peace talks and move quickly toward political negotiations according to the road map. Sharon is likely to comply with only some of Abbas’ demands. Both leaders appear ready for tomorrow’s summit but whether it will be a genuine new start for the peace process rather than the cementing of a truce is questionable.

Never to be forgotten though is that any deal between Arabs and Israelis is shaky. One act by Hamas, one brutal crackdown by Israel — or vice versa — could set off a new storm of street violence with all its depressingly familiar and destructive patterns.