Diplomats from the United States, European Union, and the Arab League said on Monday they were committed to taking military action against the Islamic State (ISIL) insurgency in Iraq, but their silence on what to do about ISIL in the group’s home base of Syria suggested the U.S.-led “united front” was still hitting snags.

Compounding that dilemma is the absence of firm commitments from crucial Sunni allies in the region about who will take an active role in military strikes, something President Barack Obama had said would underpin any U.S. military action against the extremist-led insurgency.

At a meeting in Paris on Monday, delegates from over 30 countries said in a vaguely worded communiqué they were “committed to supporting the new Iraqi government in its fight against [ISIL] by any means necessary, including appropriate military assistance.”

But there was no mention at all of Syria, the more politically complicated arena in the fight against ISIL. And with the exception of France, which has sent fighter jets on a reconnaissance mission to Iraq, none of the countries meeting in Paris has publicly agreed yet to join in airstrikes against the insurgents in either country.

Foot-dragging from the anti-ISIL coalition casts further doubt on President Barack Obama’s promise to a war-weary American public that the U.S. will secure the active support of U.S. allies, especially the region’s Sunni powers — especially Turkey, Saudi Arabia and Qatar. Washington, analysts say, would like to avoid the pitfalls of the last U.S. war in Iraq, which is seen as contributing to the current chaos.

“Ultimately this is a fight within Islam, within Sunni Islam,” White House chief of staff Denis McDonough told Fox News over the weekend. “We’ll build, we’ll lead, we’ll undergird, and we’ll strengthen that coalition. But, ultimately, they’re going to help us beat them on the ground.”

The U.S. does not believe that Sunni Arab states alone hold the answer to the Sunni problem of ISIL, said Faysal Itani, a fellow at the Atlantic Council’s Rafik Hariri Center in Washington, D.C. “They don’t, and in fact, Sunni Arab states have contributed to this problem,” he said. “What the U.S. wants is diplomatic cover to what will be a very sensitive campaign, which could be seen as targeting Sunnis.”

Progress has been slow on that front in large part because the region's Sunni powers are disinclined to help wipe out extremists who threaten to destabilize their region if it will undermine their greater strategic interests — against the Syrian regime and its foremost backer, Iran.

Even in Iraq, where those interests are more or less aligned in the short term, U.S. efforts have been hampered by varying levels of commitment to the problem, and about questions of which ground forces to partner with in such a sectarian landscape.

The road climbs steeply uphill in Syria, where countries like Turkey, Qatar, Saudi Arabia and the UAE are even more concerned than the U.S. that strikes against ISIL will inevitably bolster President Bashar al-Assad. Those states have pleaded with Washington to strike the Syrian regime since long before ISIL consolidated control over one-third of Syria and staged its astonishing takeover of huge swathes of Sunni territory in Iraq this summer.

The U.S. is finally acquiescing to calls for military intervention in Syria – but the campaign Washington envisages might have exactly the opposite impact to what its Sunni allies wanted. In Iraq, hardline Shia militias are likely to push the front line against ISIL on the ground; in Syria, barring a dramatic reversal in U.S. policy, the ground forces that retake ISIL territory could be the Syrian army. Hence the apparent ambivalence.