Editor's note: Ronald W. Zweig is Taub Professor of Israel Studies at New York University, where he is Director of the Center for Israel Studies and of the Paths 2 Peace Program.
New York (CNN) -- The details of the prisoner-exchange deal announced between Israel and Hamas -- a swap of Gilad Shalit, the Israeli soldier held captive by Hamas since 2006, for more than 1,000 Palestinian prisoners -- are not yet fully known. But after five years of failed negotiations, it is clear that both sides have made concessions. And that is a sign of hope.
The unrest in the Middle East, and especially in Syria, has been a powerful catalyst for Hamas to capitalize while it can on Israel's desire to bring Shalit home. The unrest in Damascus is forcing the external political leadership of Hamas, led by Khaled Meshaal, to relocate to the Gulf -- further away from the front lines with Israel and a political environment less sympathetic to its radical policies.
The huge upsurge of popularity for Hamas's rival, Palestinian Authority President Mahmoud Abbas, following last month's push for UN recognition of Palestine as a member state, would also have been a catalyst for Hamas to conclude an agreement by being more flexible. The return home of 1,000 prisoners, including some (but not all) of the most hardcore terrorists with the blood of hundreds of Israelis on their hands, will do wonders for Hamas' popularity -- not only in Gaza but in the West Bank and the Palestinian diaspora as well.
From the Hamas point of view, the time for a deal had clearly arrived. For Israel, the growing instability in Egypt was a factor making a deal imperative now, or a risk that it would never happen.
The Egyptians have played a major role as intermediaries, allowing both sides to negotiate without actually having to deal directly. (In the last stage of the bargaining, held in Cairo since July, Israel's negotiators sat in one room and Hamas in another, and the Egyptians acted as go-between.) The Egyptians will play a role in the actual physical exchange of the prisoners as well. Given that Cairo mobs sacked Israel's embassy there just a month ago and that the military rulers of Egypt had to be forced (by the US) to intervene, Israel has good reason to fear that Egypt's ability to facilitate the deal with Hamas might not last forever.
Another consideration was the determination by the Israel Defense Forces' new Chief of Staff, Benny Gantz, that there were no realistic military options for freeing Shalit. He was joined by the recently appointed heads of Israel's other security services -- the Mossad and the Shabak (internal security) -- who withdrew their opposition to the release of so many convicted terrorists. No Israeli Prime Minister would have overridden the unanimous recommendations of the security establishment, and the green light for the agreement from this sector was vital.
Similarly, no Israeli politician would have overridden public sentiment on this issue, but here the vast majority of Israel's public has been clearly in favor of the swap agreement for the past few years. This sentiment was skillfully articulated through a public campaign conducted by the Shalit family, their friends and associates.
Shalit's family have been camping outside Prime Minister Benjamin Netanyahu's official residence in Jerusalem for well over a year, and as they return home to prepare for the return of their son, the Israeli public cheers their dedication. Concern over the possible renewal of Palestinian terror following the release of so many skilled and determined terrorists is, for the moment at least, overshadowed by widespread enthusiasm at the return of the kidnapped soldier.
There will be celebrations in both Israel and the Palestinian territories. But what are the long-term implications of this deal?
Pessimists will point to the dangers of rewarding terror -- both the terror of those released from jail and the act of kidnapping Israelis to have future terrorists released. Cynics will ask if Israel's willingness to conclude the deal was not an attempt to punish Abbas for pushing ahead with his policies in the UN, despite Israeli and American opposition.
But there are other considerations which give grounds for optimism. Any movement in the stalled peace process might be enough to get the wheels of this heavy cart out of the rut in which it is trapped. It appears that Turkish President Recep Tayyip Erdogan had a role in the final deal, perhaps indicating a return of Turkey to constructive dealing with Israel. And the fact that Israel and Hamas have talked -- albeit indirectly -- is a welcome development. Israel's 2005 withdrawal from Gaza might have had more positive long-term effect had this channel of communication been used then.
Even more significant, the release of these prisoners removes a major obstacle from any future peace settlement between Israel and the Palestinians.
An agreement will almost certainly address the issue of the thousands of Palestinians remaining in Israeli jails. Their numbers have dropped dramatically over the past few years, as the level of violence in the occupied territories has declined -- from 11,000 in 2008 to just over 4,000 after the current prisoner swap is completed. But freeing almost all of the most dangerous prisoners now, in circumstances that will be endorsed by Israeli public opinion, means there is one less impediment to be dealt with in the final settlement.
The opinions expressed in this commentary are solely those of Ronald W. Zweig.