The winds of change are unexpectedly blowing through the Levant.

In the aftermath of the Iran nuclear agreement, there was a broad expectation, both in the region and beyond, that sectarian tensions and conflict would intensify and deepen the proxy battle between Iran and Saudi Arabia. In the United States, even some strong supporters of the nuclear deal emphasized that Washington needed to respond aggressively to the inevitable push by Tehran to expand its regional influence at the expense of traditional U.S. allies.

What we are seeing on the ground, however, looks quite different. There is an increasing possibility for new geopolitical alignments throughout the region. The confluence of the growing fear in both Saudi Arabia and Iran of the threat posed by Islamic State; the weakening of President Bashar al-Assad’s regime in Syria; Turkish President Recep Tayyip Erdogan’s policy shift to cooperate with the United States in Syria, and Moscow’s and Washington’s growing shared interests in steering the Saudi-Iran rivalry onto a less escalatory path, while also creating a broad coalition against Islamic State, is creating real political fluidity.

As diplomatic moves accelerate, the United States and its allies look to be preparing a serious onslaught on Islamic State in both Iraq and Syria. The opening of Turkish air bases to coalition aircraft, manned and unmanned, will enable the allies to prepare for a major ground offensive by local allies to recapture Mosul. Iraq’s third-largest city has been under Islamic State control for more than a year. More inchoate is the parallel jockeying around Syria’s political future, and whether a compromise framework can be found to end that country’s civil war.

The first sign that a diplomatic offensive was in the works was President Barack Obama’s fulsome praise of the Russian role in the endgame of the Iran negotiations during his interview with New York Times op-ed columnist Thomas Friedman. This was reciprocated by the Kremlin ratcheting down the virulent anti-Americanism that had dominated its narrative of world events since the annexation of Crimea and the imposition of Western sanctions last year.

Then both Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov were recently in Doha to meet with Gulf leaders, which included a joint meeting with their Saudi counterpart. This was followed by a visit to Riyadh by Assad’s intelligence chief and the dispatching of the Syrian foreign minister for meetings in Oman, the only Gulf state not actively supporting anti-Assad rebels in Syria.

Critical to the new diplomacy is the flurry of unusual diplomatic activity between senior Russian and Saudi officials in recent months. In the aftermath of Saudi Arabian King Abdullah’s death in January, the Russians sought to explore prospects for Saudi flexibility in Syria. The new Saudi leadership, expecting a nuclear deal with Iran and frustrated with the United States, looked to test whether Moscow was willing and able to moderate Iranian regional policy. The Saudis are particularly focused on Yemen, which is critical to Saudi security and where anti-Saudi Houthi rebels had taken control, with what Riyadh believes was direct Iranian support.

The rapidity with which Saudi Arabia has, unlike Israel, dropped its active opposition to the Iran nuclear deal speaks to the importance it gives to the new regional diplomacy. Recent apparent successes by the Saudi-led military force seeking to drive the Houthis out of power, if consolidated, may provide the Saudis with the confidence they need to give on-the-ground momentum to the new diplomatic momentum building in the region.

It is still too early to tell what role Iran intends to play. In the nuclear negotiations with the six world powers, regional issues were explicitly excluded from the discussions to maximize prospects for success on the nuclear front. But some Western leaders, particularly Obama, clearly hoped that a successful conclusion of the talks might create space for a broader diplomacy. Obama also expressed his view that a solution to the continuing conflict in Syria requires Iran’s participation at the negotiating table, a reversal of his previous position.

The regime in Syria would not survive without Iran’s contributions in manpower and armaments. Hence, it seems unlikely that the recent initiatives would have taken place without Tehran’s acquiescence, at minimum. Iraq, which also coordinates closely with Iran, recently assured visiting Defense Secretary Ashton Carter that Sunni militia would play a significant role in the coming offensive to retake Anbar province from Islamic State, with Shi’ite militias playing a less prominent role. Both the United States and Saudi Arabia had been urging just such an approach on Baghdad.

It remains uncertain whether Iranian hard-line elements, especially the Revolutionary Guards, will go along with a policy of cooperation, especially one that may endanger the Assad regime and, by extension, Iran’s most prized ally, the Hezbollah militia. Nor will the Russians easily jettison their ally Assad. This was clear in Lavrov’s comments that the Syrian strongman is a perfectly acceptable partner in fighting Islamic State.

Recent diplomacy notwithstanding, we remain a long way from resolving the complex problems emanating from the Syrian civil war and the weakening of the Iraqi state. But a critical test will be the speed and extent of success that is achieved in the coming offensive against Islamic State. The militant group is unlikely to be eradicated completely. But if its hold on large parts of Iraq and Syria are broken fairly quickly, momentum would shift and Islamic State would be a substantially weakened adversary.

Ironically, such an outcome would make the Assad regime in Syria more vulnerable. Without Islamic State breathing down its neck, the opposition forces would be freed from fighting a two-front war.

This is the ultimate paradox: By threatening everyone, including the Iranians and the Russians, Islamic State will have succeeded in uniting all to defeat it. Yet the price down the road for both countries will be increased pressure to abandon the Assad regime.

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© Reuters. Henri J. Barkey is director of the Middle East Program at the Woodrow Wilson International Centre for Scholars. David F. Gordon is a former policy planning director for Secretary of State Condoleeza Rice and former vice-chairman of the National Intelligence Council. He is now senior advisor to the Eurasia Group. The opinions expressed here are their own.