This week’s announced willingness by the chairman of the rebel Syrian National Coalition to negotiate Syria’s political transition with officials of the current government was the first hopeful sign that the country’s deadly two-year civil war may yet be brought to an end.

Yet the Israeli air strike the same day on weaponry reportedly destined for Hezbollah’s militia in Lebanon underscores the volatile regional interests that are also at play. For if one cannot achieve a peace settlement without the acquiescence of Syria’s warring adversaries, that accord may be equally difficult to achieve if the interests of those adversaries’ foreign backers are not dealt with as well.

Lakhdar Brahimi, the special envoy of the United Nations and Arab League who has been working since August to marshal external pressures on the internal combatants to shut down the war, spent much of the past week in New York gloomily briefing the Security Council on a peace process that was dead in the water. The war, he told the council amid media reports of new mass executions in Syria, had reached “unprecedented levels of horror.”

But American and Russian diplomats remained at an impasse on how to bring into a transition process the government and its armed opponents, who have adamantly refused to talk to each other, along with the many Syrians who fear both.

The announcement by Ahmad Moaz al-Khatib, chairman of the coalition seeking the overthrow of president Bashar al-Assad’s Baathist regime, that “I am ready for direct discussions with representatives of the Syrian regime” seemed to be the first opening toward a political process. Although Khatib had not cleared his shift with the many contentious factions of his coalition, and some among them were quick to denounce it as a betrayal, Brahimi swiftly arranged an unprecedented top-level meeting for Khatib with U.S. Vice-President Joe Biden and Russian foreign minister Sergey Lavrov.

The Biden-Lavrov meeting with Khatib and Brahimi is intended to send the message to Assad that he must begin the transition process with the Syrian National Coalition, and to the coalition’s hardline rebel factions that they will have far better chances of replacing Assad’s government if they enter a political dialogue with it than if they continue a grinding war in hopes that it completely disintegrates. For the Americans, the meeting telegraphs their walking back from the position that Assad must depart in order for negotiations on Syria’s political transition to commence—the position that the Syrian opposition forces have insisted on till Khatib’s declaration Wednesday.

The Russians now have the burden of bringing Assad into negotiations that will inevitably focus on the modalities of his handover of power. The government in Damascus has already reacted with outrage to Brahimi’s public acknowledgment that Assad’s relinquishment of authority is the inevitable end-game. Brahimi has proposed face-saving arrangements, such as replacing the presidential regime with a parliamentary one to transfer executive authority—and particularly control of the security services—to a council of ministers.

Western diplomats at the United Nations sense that the insurgents’ momentum has stalled, or at least that the government has had some good weeks recently. Jordanian King Abdullah, too, last week derided armchair analysts’ assumption that the Assad security state is on the brink of collapse: “Anyone who says that regime has got weeks to live doesn’t know the reality on the ground.”

Both Abdullah and Western governments are alarmed, too, that Al Qaeda jihadists are coming to dominate the insurgency. Already external recruiters for the Syrian jihad are girding for battle with secular elements in the Free Syrian Army when the Assad forces collapse.

The jihadis are particularly excited that victory in Syria would at last put them directly across a border from the “Zionist entity,” a feverish dream of Islamist zealots. No wonder the Israelis are deeply ambivalent about Syria’s upheaval.

The Assads’ regime has scrupulously maintained the forty-year truce and offered a peace accord with Israel premised on return of every square centimeter of the Golan Heights—which the jihadis cite as evidence of its de facto collaboration. Yet absent such an agreement Damascus has served as an arms supplier, and the conduit for Iranian weaponry, to the rabidly anti-Israeli forces of Hezbollah in Lebanon. Few Israelis expect peace-minded liberals to emerge on top in a post-Assad battle for power, and a prolonged and violent civil war may not strike them as the worst scenario.

Their air strike this week reminded the Syrian factions—and meddlesome other nations—that Israelis are ready to respond preemptively to any emerging threats, particularly those connected with Iran. The Iranians have been deeply concerned that they might lose their staunchest ally in the Middle East, and with it the leverage they have acquired as arms patrons of Hezbollah. Over the past year Iranian diplomats have telegraphed that they are not mortgaged to the Assad family, even as Tehran has readily re-supplied Damascus with critically needed armaments.

Last year Kofi Annan, then the U.N. special envoy, insisted that Iran needed to be part of the international contact group he sought to assemble that would coordinate their pressures on the Syrian factions to compromise. Iran, he argued, has at least as much influence with Assad as has Russia, and if not involved in the solution would have both means and motive to intensify the problem.

Iran’s inclusion was unpalatable to an Obama administration committed to Tehran’s isolation, but the president’s renewed mandate should allow his new secretary of state to take a different course. From a Russo-American convergence on a Syrian political transition, if it emerges the Khatib initiative, needs to be enveloped in a consultative mechanism that includes Iran and Saudi Arabia (the insurrectionists’ main supplier) if it is to succeed in shutting down Syria’s disastrous war.