Alessio Romenzi for TIME A Free Syrian Army's sniper position, in Al Qsair, on Feb. 9, 2012.

“It is time we gave them the wherewithal to fight back and stop the slaughter,” said Senator John McCain on Monday, referring to Syria’s opposition amid the carnage being wrought by the Assad regime’s efforts to quash a year-old rebellion. But McCain’s call is unlikely to be heeded by the Obama Administration or other Western governments as they prepare for Friday’s inaugural meeting in Tunis of a “Friends of Syria” forum established to coordinate an international response to the crisis. That’s because Western decision-makers are not quite sure just who the Syrian opposition would be — there is no single leadership that speaks on behalf of those fighting the regime on the ground in cities across Syria, and there are certainly signs that its ranks may include elements deemed hostile to the West. And also, because it’s far from clear just how arming rebel forces would, in fact, “stop the slaughter” and not intensify it.

The problem confronting international stakeholders as they grapple for a response to the slow-moving bloodbath is that there at least three different narratives playing out at the same time in Syria, each of them complicating the others. There’s the narrative of the brutal authoritarian regime confronted by a popular citizens’ rebellion that it has been unable to crush despite a year of slowly escalating repression — a crackdown that has wrecked the country’s economy and made it impossible for the regime to restore stability, much less regain its legitimacy. (Nobody’s expecting the constitutional referendum to be staged by the regime on Sunday to yield a credible popular mandate for Assad’s rule.)

(SEE: Exclusive photos of the Syrian civil war.)

Then there’s the narrative of sectarian warfare, in which Syria’s ethnic and confessional minorities — the ruling Alawites who dominate the regime and its security forces, but also the Christians, the Kurds, the Druze and smaller sects — shudder in the face of a predominantly Sunni rebellion in which they see a specter of sectarian retribution that prompts many of them to remain on the sidelines or support the regime for fear of the alternative.

And finally, there are the geopolitical stakes, as the Sunni monarchies of the Gulf see an opportunity to hobble their Iranian nemesis by helping their indigenous allies overthrow a Tehran-backed regime. Syria also becomes an arena for China and Russia to block the expansion of Western influence in the Middle East through toppling regimes.

On arming the Syrian opposition, then, it’s probably going to happen regardless of what Western powers decide — it’ll be undertaken largely by Gulf powers such as Saudi Arabia and Qatar, which played a major role in boosting the Libyan rebel forces on the ground in the battle to oust Muammar Gaddafi. And the Russians will continue to arm the Assad regime, unwilling for their own geopolitical reasons to countenance his ouster. Russia has declined an invitation to attend Friday’s discussion in Tunis, giving as its reason the fact that the Syrian government was not invited. China has yet to respond, but it, too, has supported seeking a political solution through dialogue with the regime, rather than forcing it out of power.

For Western and Arab powers — as well as the main exile-based opposition group that they appear to be moving towards recognizing as as an alternative, the Syrian National Council — the time for negotiating terms with Assad has passed. Obviously, Assad doesn’t agree, nor do his backers in Moscow and Tehran. And his forces’ sustained bombardment of rebel-held suburbs of the city of Homs despite a U.N. General Assembly resolution demanding a halt to repression is a sign that the regime is still trying to crush the rebellion through a massive concentration of force. Instead, however, the uprising appears to be spreading, with protests last weekend reaching into previously passive, well-heeled neighborhoods in Damascus. Still, despite the slow but steady decline of its control over all of Syria, the regime’s security forces remain dominant: they are unable to eliminate the rebellion, nor are they in any immediate danger of disintegrating.

(PHOTOS: After Homs, Syrian rebels regroup.)

Western powers clearly want the Assad regime to go, but not in such a way that a power vacuum is created that may be filled by elements less predictable and more hostile to the West than Assad has been. On that score, the public commitment of al-Qaeda to the cause of the Syrian rebellion, and the belief in the U.S. intelligence community that the jihadist network was responsible for two high profile bombing attacks in Damascus and Aleppo, has given Washington’s security establishment pause over the wisdom of helping militarize the rebellion. Indeed, reports from Iraq suggest that violence there has dropped sharply in recent months precisely because Sunni jihadists have crossed the border to turn their guns on the Assad regime.

But for those arguing most forcefully for arming the opposition, a related problem is that there’s no credible address right now for such aid. Not only is the extent of the Syrian National Council’s authority still in question, but the Free Syrian Army — the predominantly Sunni insurgency which operates separately, and is led (to the extent that it has a chain of command) by defectors from the regime’s forces — doesn’t appear to exercise much control over many of the units of armed volunteers on the ground that fight under its rubric.

France and Turkey have suggested the possibility of creating some form of humanitarian buffer zone inside Syria, that would allow aid to reach beleaguered cities such as Homs — but as things stand, even setting such ostensibly more modest goals would require a willingness that has not yet been evident to undertake direct military intervention. (Right now, instead, the International Red Cross is trying to negotiate a daily two-hour cease-fire in order to ferry aid to the civilian population of Homs with the consent of the Assad regime.)

The political solution as envisaged by the Arab League involves Assad stepping down and yielding to a democratic process, but the balance of power on the ground has not yet made that an inevitable outcome.

Some, such as George Washington University Professor Marc Lynch, who advised the Obama Administration on its Libya intervention, suggest that the key to breaking the deadlock may be to avoid further militarizing the situation which would harden the polarization, and instead focus on strategies that weaken the regime politically. The key to Assad’s continued power, says Lynch, is that Syrian society is deeply divided. Loosening his grip will require strategies that reverse or neutralize that polarization — which armed intervention or boosting rebel fighting capacity is unlikely to do.

But evolving a strategy to achieve a “soft landing” and build a post-Assad consensus for Syria may not offer much immediate relief to the Sunnis of Homs, who are likely to be bleeding and dying as their “Friends” convene on Friday in Tunis.