If past Fatah-Hamas "kiss and make-up" sessions are any indicator, this one will have the life expectancy of a fruit fly.
No sooner did the secular Fatah try to sell the agreement as a move toward peace than the Islamist Hamas declared the opposite.
In the realm of odd bedfellows, the winners appear to be the terrorist group looking for international acceptance, its Iranian mentors and Israel's right wing, some of whom are calling for extensive West Bank annexation and economic sanctions in retaliation. None is interested in a peace agreement that would see two states, Israel and Palestine, living side by side in peace.
Fatah and Hamas have signed reconciliation pacts in the past only to see them quickly collapse.
Factors bringing the two sides together this time include Fatah's frustration with the deadlocked peace process, which it blames on weak American and Israeli leadership, and Hamas' realization that the change sweeping the Arab world is led by liberal, secular forces -- and not by authoritarian Islamists like itself -- plus the prospect of losing its patron and sanctuary in Syria.
Prime Minister Benjamin Netanyahu must be pleased that Abbas has rescued him from having to offer dramatic concessions to launch serious negotiations when he comes to Washington later this month. And it now appears doubtful that President Barack Obama, who was the target of a scathing attack by Palestinian Authority President Mahmoud Abbas in a Newsweek interview for his handling of the peace process, will be inclined to produce his own peace initiative to pre-empt Netanyahu's speech, as was expected only a week ago.
Abbas insists that he's in charge of the peace process regardless of Hamas' rejection, but he knows that no Israeli government can negotiate with -- much less make concessions to -- a Palestinian government half-controlled by a terrorist group committed to the three no's: no recognition, no negotiations, no Israel.
As a top Hamas leader, Mahmoud al-Zahar, said: "Our program does not include negotiations with Israel or recognizing it."
Even before their agreement was signed, Hamas began pressing Abbas to rescind PLO recognition of Israel. The two bitter rivals have diametrically opposed goals. Fatah seeks a secular national state, and Hamas wants to create an Islamic republic. Their differences were emphasized this week when Fatah welcomed the death of Osama bin Laden as "good for the cause of peace," and Hamas condemned the American assassination of "an Arab holy warrior."
Abbas sees the unity government as bolstering his strategy of winning U.N. recognition of statehood this fall -- something strongly opposed by Washington and Jerusalem.
Hamas is demanding that Prime Minister Salaam Fayyad, the only P.A. leader with any credibility when it comes to finances, security cooperation and institution-building, leave office as a condition for the unity government.
A major concern for Israel is the possible integration of Hamas figures into the U.S.-financed P.A. security forces, which until now have earned Israeli praise for professionalism and cooperation.
The agreement calls for an interim government of technocrats to run things until parliamentary and presidential elections can be held some time next year. For Hamas, this will be an opportunity to re-establish its political -- and terror -- infrastructure on the West Bank, especially if Fatah agrees to demands to release hundreds of Hamas prisoners.
With Hamas a partner in the Palestinian Authority, how will Abbas respond when his new allies fire rockets into Israel? What happens when Israel hits back?
No matter how he tries to frame it, Abbas is surrendering to Hamas rejectionists and betraying everything he has said he stands for -- a negotiated peace, two states, a rejection of terrorism.
Those who insist that a Fatah-Hamas unification will chart a new course toward democracy should recall the expectations that Israel's withdrawal from Gaza would provide Palestinians with a showcase for democratic development, not a terrorist base and missile launch pad.
Abbas shrugs that off and insists that his marriage of convenience will enhance his chances for U.N. recognition. If it lasts that long.
Douglas Bloomfield is a syndicated columnist based in Washington, D.C.