Blood continues to flow in Syria. Reports this morning are of further massacres, in the villages of Qubair and Maarzaf, with perhaps another 80 people killed — among them many women and children.

It’s not possible to verify all of these reports, but while nobody pretends that the Syrian opposition are saints, the regime’s claims that violence is all the work of foreign-inspired “terrorists” are simply not credible. When bloodshed on this scale is happening in a country, something is badly wrong with its government, and things need to change sooner rather than later.

Almost as infuriating as Bashar al- Assad’s cheer squad, however, is the chorus of commentators now insisting that the west should “do something” without stopping to explain just what can be done and how it’s supposed to avoid making matters worse. Sometimes western intervention works. They still have their opponents, but it seems to me that going to war both for Bosnia in 1999 and Libya last year were the right decisions and produced beneficial results. Against those must be set the disasters of Vietnam and Iraq.

Bosnia and Libya were both more like conventional wars, with a rebel force controlling territory on the ground that could be supported from the air. Syria is much messier: not even a proper civil war, but civil conflict among a variety of armed groups, with both a well-armed government and ruthless militias supporting it. As Marc Lynch put it in April, “there are no front lines to police, few tank convoys to destroy on desert highways and no offensives by rebel armies for which an air campaign would clear a path. Regime forces and the opposition are primarily clashing in densely packed urban areas.”

I can’t recall an example where foreign intervention has been attempted in a case like this. At least, not on the side of the rebels — the 1979 Soviet invasion of Afghanistan is not a bad analogy, but that was on the side of the government. And we know how well that turned out for everyone concerned.

More thoughtful words on the possibilities of intervention come this week from Michael Kinsley:

“Too often, when we weigh the costs and benefits of intervention, we take credit for our intentions rather than the results. Whether the invasion and occupation of Iraq would have been worth the costs if we were leaving behind a stable democracy as promised is a very different question than whether the war was worth it as it actually turned out.”

Also worth reading is a long piece from the BBC by PJ Crowley, a former US Assistant Secretary of State. Comparing Syria with Bosnia, Crowley offers the depressing thought that “the present situation could resemble not 1995 but 1993, when the conflict was still accelerating.”

Much as the neocons love to hate on the United Nations, it can’t be said often enough that actually doing something effective about Syria, as distinct from feel-good posturing, is going to require international co-operation, and that’s a slow and frustrating process. Kofi Annan’s peace plan was a step in the right direction: it did at least stem the violence for a while, and its collapse puts Assad more firmly and publicly in the wrong, opening up possibilities for further pressure.

The key, of course, is Russia. A Bloomberg report yesterday, reprinted in today’s Age, suggests that the Russians are getting ready to cut Assad loose, attributing to the deputy foreign minister the view that “his country has never insisted on Assad staying in power and a decision on his future must be taken by the Syrians themselves”, and quoting Fyodor Lukyanov, a Russian analyst, that “A managed change of regime is the only option now.”

Russia’s goals are reasonably clear. It wants a friendly government in Syria, it wants its own geopolitical importance to be affirmed, and it doesn’t want to be seen to be pulling the rug from under an ally. On the other hand, Assad is clearly becoming more and more of an embarrassment, and continuing instability is as harmful to Russia’s interests as anyone’s.

In principle, it should be possible to reconcile those aims by some sort of managed transition of power in Syria. It would make sense to continue to downplay the idea publicly while privately pushing Assad to agree to a deal that would see him leave power in return for some guarantees for his family’s wealth and safety.

But embattled despots have a habit of not listening to that sort of advice until it is too late.