Bashar al-Assad has failed to quell a stubborn rebellion despite his regime's massive edge in military manpower and weaponry -- but also because of these material advantages. His forces, replete with heavy armor, attack aircraft, and big guns, have tried to use something akin to our Powell Doctrine of "overwhelming force." Yet the insurgents' nimble, loose-jointed networks of small cells have slipped most of the heavy punches thrown at them, and they have launched increasingly stinging counter-blows of their own.
How is it possible for such a ragtag movement to persist? Without the kind of NATO-provided close air support the Libyan rebels enjoyed? The answer lies in the fact that the Syrian military, like armed forces of most nations, is organized into a few large, bulky units, while insurgent cells are smaller and far more fluid. Thus the Syrian Army, most of whose striking power is concentrated in eight tank divisions, has a terrible time trying to deal with the "pop up" attacks by roughly 1,000 eight- to ten-man rebel fire teams. Air strikes against small bands of fighters are problematic, especially in urban terrain -- resulting far more in the killing of innocents than of insurgents.
That the rebels are receiving increasing numbers of anti-tank weapons -- and perhaps now a few shoulder-mounted anti-aircraft missiles -- makes them increasingly deadly. But their real advantage lies in being able to launch offensives simultaneously in half a dozen Syrian cities. We hear mostly of the fighting in and around Damascus and Aleppo, but the rebellion is flaring all around the country -- and the regime hasn't yet figured out how to scale down its forces into smaller units and deploy them widely enough to tamp down these hotspots.
In short, the insurgent network is swarming regime forces, like killer bees, or ants overwhelming a crippled beetle. Analogies from nature aside, the simple math of the Syrian civil war is that the rebels attack many points at the same time, while the Syrian military is only able to focus its counterattacks on a few points at any given moment. For the regime, this is a losing proposition in the long run. Bashar al-Assad still has a large, well-armed military, and the Iranians and Russians will likely keep restocking his arsenals for a while. But unless he can create a counter-swarm of his own, his days are numbered.
However certain Bashar's ultimate downfall may be, it is not imminent. The insurgents' principal strength, their network of small cells, is also their main weakness, as the diverse bands of fighters lack a unifying narrative to cement their common purpose. The simple story of an oppressed people struggling to overthrow a tyrant is complicated by the desire of some insurgents to settle old scores with the long-ruling Alawite minority, and the visceral hatred others have for Syria's sizeable Christian community. The presence of al Qaeda fighters is a wild card that further complicates the prospects for direct external military intervention, and makes even choices about better arming the rebels highly problematic. Mitt Romney has spoken of giving aid to the "good insurgents," but they are very hard to distinguish clearly.
Another difficulty for the insurgency is that Bashar has a network of militiamen, the shabiha, able to make great mischief. But his use of them quickly backfired. Bashar began the conflict by launching the shabiha against nonviolent demonstrators; as their name suggests (it translates roughly as "thugs"), they have behaved very badly, beating, raping, and murdering protestors -- actions that only fanned the flames of insurgency. While the shabiha are still out there -- and still pose serious problems for the rebels -- the social damage they inflict with their depredations is too great. In short, they have the kind of organizational structure best suited to fighting the insurgents, but their actions, on balance, do far more harm than good to the regime.