Vigil held for the Jordanian pilot in South San Francisco, February, 2015. Steve Rhodes/Demotix. All rights reserved.Successes against the Islamic State in Diyala, Sinjar, and Kobane as well as the burning alive of Muath al-Kasasbeh have galvanized calls for Middle Eastern states to commit ground troops. In a recent interview, Senator John McCain, the chairman of the Senate Armed Services Committee, expressed his hope for a ground force comprised of Turkey, Saudi Arabia, Jordan, and others to take the fight to IS. However, major obstacles preclude such a scenario. The coalition’s best bet is a well-trained, well-equipped local force that benefits from coordinated coalition airstrikes and solid intelligence.

Mr. McCain’s view is certainly not isolated. Hassan Hassan, co-author of ISIS: Inside the Army of Terror, told me that “boots on the ground are of course necessary,” Hassan invoked the example of the Anbar province where airstrikes have done little to stop IS from entrenching and even expanding its hold on territory. However, unlike Iraq there are no reliable local forces to coordinate with in Syria at the scale necessary. Which partly explains the call for Middle Eastern states to participate in the fight.

A very serious obstacle, however, remains in the form of the question of President Bashar al-Assad’s fate. This is a question with apparently diminished relevance for a world stunned by the nihilism of IS, never mind that Mr. Assad’s forces have displayed brutality that far supersedes IS in kind and scale. In any case, the participation of Middle Eastern forces depends in large part on which of the following two options the coalition will adopt in deciding the fate of Mr. Assad.

First, a negotiated settlement. Russia and Iran have extended a critical lifeline to Mr. Assad, and without a negotiated settlement that lays the foundation for ground forces, the likelihood of coalition forces engaging between the Syrian army and its allies significantly increases. In such circumstances it’s difficult to imagine Qassem Suleimani sitting idly by fiddling his thumbs while Sunni states invade Syria to depose Mr. Assad. This is a nightmare scenario that would ignite a regional conflagration which would quickly involve a reluctant United States.

Is it possible then to strike a deal with Mr. Assad? Well, interviews he has granted recently to the BBC and Foreign Affairs magazine reveal a man so completely detached from reality that it’s very hard to see him as part of a solution. According to Jonathan Tapperman, who conducted the interview for Foreign Affairs, Mr. Assad occupies a “Neverland” of his own imagination. He is “ready to concede absolutely nothing to bring the sides together.” In other words, there is no reasonable deal to be had with the Syrian president.

The second option is a military intervention that defeats Mr. Assad. This, however, is even less likely than a negotiated settlement. A military intervention is effectively vetoed by both Moscow and Washington, and Iran remains a considerable menace. Some might suggest that the option of training the moderate opposition remains. But for structural, political, and logistical reasons the moderate opposition - or whatever remains of it - cannot be made capable of such a task in the short to medium term.

Therefore, a complete military defeat of Mr. Assad is out of the question. And his intransigence seems to deny a deal in which the Syrian government makes serious concessions. Without a satisfactory answer to the question of what to do about Mr. Assad it becomes very difficult to imagine a scenario in which countries like Turkey, Saudi Arabia, the United Arab Emirates, Qatar, and Jordan commit ground troops to the fight against IS.

Even if we suppose that the international community musters, miraculously overcoming Russian objections to removing Mr. Assad militarily, what of Iran? The US is engaged in high stakes talks with Tehran. The administration deems these negotiations so important it’s willing to risk a very public rift with Israel before jeopardizing them. A military intervention against Iran’s ally in Damascus would bring the negotiations to a screeching halt, or negate any kind of accord that emerges from them.

On the other hand, even if an arrangement with Mr. Assad is reached - one that is blessed by Russia and Iran, the participation of Middle Eastern states in a ground effort against IS remains in question. According to Mishaal Al Gergawi, managing director of the UAE-based Delma Institute, there is the concern of domestic standing and political upheaval if these armies are bogged down in a long and bloody conflict.

Others I’ve spoken to highlight disagreements that exist among these states. Turkey, for example, has to be a key member of any ground effort but without abandoning its long-standing antagonism towards the Egyptian government and its Arab allies, the chances of an allied ground force quickly dissipate. Ultimately, Turkey’s own involvement without a coalition commitment to remove Mr. Assad makes this a pipe-dream.

Discussions of Middle Eastern states committing troops to the fight against IS seem, at this point, to be nothing more than navel-gazing. Mr. Obama stated in his remarks on the war authorization request he put to Congress that “local forces…are best positioned to take the ground fight.” The president was being generous, local forces are not merely the best positioned, in fact they currently represent the only option.

So for the meantime the coalition has to deepen and widen its training and arming of local forces.  According to the Pentagon, fighters undertaking US-led training will not return to Syria for another 8-12 months. A recent report in the Wall Street Journal revealed that the CIA-led program to train moderate rebels has effectively collapsed, which forces one to ponder the fate of the military-led program. Finally, as Hassan put it to me, Middle Eastern troops “might be an eventuality if there is a serious will to annihilate ISIS.” Try as we might then, the question of Mr. Assad’s fate will not go away: all roads stubbornly lead back to Damascus.