For over a quarter of a century Prime Minister Netanyahu had promised, boldly and unequivocally, both in writing and in speech, that he would never make any concessions to terrorists. Now, in one fell swoop, with the negotiated release of Gilad Shalit, all that is gone. The Prime Minister himself cast it as a momentous choice, an instance of decisive and historic leadership.

But the reason Netanyahu that gave for his decision, namely that "circumstances had changed", betrays considerably more anxiety. Indeed, the phrase is marked by its very passivity, and an unmistakable suggestion that Israel was reacting to shifts in the region. Of course, the more operative question right now is not what motivated Israel to negotiate, but rather how much the experience of negotiations will now motivate Israel. Yes, “circumstances had changed,” but it’s more important to consider the role Israel should play in shaping regional circumstances going forward.

The last ten months have seen radical strategic changes in the Middle East that have weakened the positions of all the players in the political arena. Hamas has experienced a series of major setbacks. Its political and strategic base in Damascus has become extremely vulnerable amidst the political upheaval there. Hamas has been in the uncomfortable position of having to choose between supporting their patron Bashar Assad, and the Sunnis who are rebelling against him and with whom they share a religion. Meanwhile, Tehran seems to have begun  losing interest in Hamas: Iranian arms still flow into Gaza, but the Islamic Republic’s cash flow has stopped, leaving Hamas unable to service the monthly salaries of many of its supporters. Hamas desperately needed a game-changer.

The Egyptian military government, for its part, is gingerly feeling its way through the post-Mubarak era, negotiating between the masses of Tahrir Square, the traditionally powerful and now fully legalized Muslim Brotherhood. Eager to assume once again its role as a traditional leading player in the Arab world, Cairo was glad to play a key role in brokering the Shalit deal.

Then we had the Palestinian Authority led by Mahmud Abbas. Having just had led an anti-Israel and anti-American campaign to bypass direct negotiations with Israel and obtain U.N. recognition for a Palestinian State regardless, the PA has been tempting a diplomatic backlash from its financial patrons in Washington, and its powerful neighbor.

The United States’ changing role in the region has also played a part. Despite its longstanding opposition to negotiations with terrorists, Washington may have thought this would be a good time to permit a slap on the wrist to Mahmud Abbas, in partial response to his obstinate push for recognition of Palestinian sovereignty in the U.N., which was initiated against the express wishes of the U.S.—and which Washington has promised to veto when it comes up for a vote in the UN Security Council .

And lastly, there’s Israel, which had endured a series of setbacks in the Middle East, amongst others, a crisis in its relations with a long term key ally, Turkey, a renewal of a Fatah–Hamas pact which has been anathema to successive Israel cabinets, and a bumpy stretch with Cairo as epitomized by the storming of its embassy there. Jerusalem was increasingly desperate for a new strategy, one that would end its growing marginalization in the region.

The Shalit deal emerged out of the changes experienced by these five players. It is telling that only Mahmud Abbas who was outmaneuvered and isolated throughout the negotiation process. It was equally telling that his first reaction upon hearing about it was to call up Khalid Mashal, the head of Hamas, and ask for a meeting with him.

These players will now have to determine whether this will remain an isolated event. Hamas has already indicated that it would like to explore the possibility of a wider and ambitious set of negotiations: Leading Hamas figures have mounted a very public campaign, one that the entire Israeli public has been exposed to, offer the possibility that they will abandon all terror and violence. Mashal’s public appearances in Cairo have been especially diplomatic and humane.

Clearly, Hamas would like many more prisoner releases, and an end to the blockade of Gaza. But what the group has yet to suggest is what they will offer in return. Will they ultimately conclude that the kidnap of a soldier has paid handsome results and will they try for more of the same? (Evidence suggests they might: The released Palestinian prisoners were greeted in Ramallah , the seat of the Palestinian Authority, with deafening cries of "We want more Shalits!") Or will Hamas instead abandon terrorism for politics? Moreover, will other players in the region encourage them to do so?

The greatest tragedy would be if these questions remained purely speculative. Israel now has a golden opportunity to reframe its strategy and to refresh its diplomatic aims to match the new regional realities. No longer can it simply take for granted the continued exclusion of Hamas from the political equation. Hamas is striving to behave and be accepted as a legitimate political actor, and Jerusalem will have to consider whether it can ever negotiate peace with the Palestinians without Hamas at the table, together with Palestinian Authority. It’s certainly not the case that Israel lacks leverage against either. If it’s the release of prisoners that the Palestinians respond to, there are thousands of Palestinians still in Israeli jails, including leading figures of both Fatah and Hamas, which could potentially be the subject of further negotiation.

The sad truth is that if Israel doesn’t seize this chance, if it treats this deal as an isolated event, as irrelevant to the political process, we can already guess how things will end: Hamas will most likely conclude that it has no option but to revert to its old ways, and the possibility of a revised regional order will be forestalled, to everyone’s detriment. Netanyahu seized the opportunity to end the Shalit saga because, as he put it after the exchange, he felt the chance might never return. Surely, therefore, he should not disregard the bitter lessons of history, which show that circumstances always change,  but sometimes for the worse.    

Efraim Halevy is head of the Center for Strategic and Policy Studies at the Hebrew University of Jerusalem. He served as chief of the Mossad from 1998 to 2002, and is the author of Man in the Shadows: Inside the Middle East Crisis with a Man who Led the Mossad.