Foreign powers did not invent Syria’s uprising, but they are certainly helping it along. In recent months Turks, Arabs and Americans have embraced the rebel cause, pumping in a thickening flow of weapons and helping to discipline the once ragtag insurgents into a force that grows more potent by the day.

 

The Gulf state of Qatar has mobilised its special forces to provide logistics and training, as it did in Libya. Saudi Arabia has gone further, helping to set up a new command centre in Adana, a Turkish city 60 miles from the Syrian border, to oversee the provision of training, intelligence and arms to the Free Syrian Army, the name given to the loose rebel network of local militias and anti-Assad defectors. President Obama, having watched warily at first, has now signed a presidential “finding” that authorises greater covert, albeit non-lethal, assistance.

 

As Assad’s forces encircle Aleppo and bomb its neighbourhoods from the air, it’s easy to understand why such decisions have been taken. But proxy wars carry risks, and even those of us who are sympathetic to the rebel cause must recognise this. The shadow of Afghanistan, another country where Saudi Arabia and the United States cooperated to aid fragmented rebel forces, hangs over present-day Syria. Those efforts, labelled “ghost wars” by the journalist Steve Coll, succeeded in toppling a government, but also contributed to decades of instability, emboldened radical Islamist groups, and had consequences far beyond Afghanistan’s borders.

To be sure, Syria has some advantages...