There is debate over whether Aleppo is Syria's largest city, but it is certainly its richest. Sitting near the northern border with Turkey, Aleppo is to Syria what New York City is to the US --- a key financial hub, and a key crossroads for international trade.
Now Aleppo is nearly surrounded by fighters from the Free Syrian Army, and there are battles, albeit small, in the city's streets.
Aleppo has long been considered an Assad stronghold, but this has not been the case for many months. Protests have been growing steadily, and in recent weeks between 1 and 3% of the city's population has taken to the streets in the demonstration. With dozens killed and many hundreds arrested by regime forces, it is now fair to say that these protests represent the tip of an iceberg.
Initially, opposition supporters felt very weak, as if the entire city had eyes and was watching Assad's back. By late winter, however, the general consensus --- among EA's sources and in reports from observers --- was that many of the wealthier business people in the city were afraid rather than supportive of President Assad, fearing that they would lose everything if those backed an uprising that was far from certain. Many of those people have come to realize that Assad cannot end this crisis. Some are appalled at the brutality of the Assad regime, a regime they trusted to lead reforms. So the question is whether fear has given way not only to cautious neutrality, but to an embrace of the opposition.
The regime is in a worse position in some ways than in Damascus. First, the opposition never had full control of cities or towns around Damascus, even before recent fighting. Second, the capital is far from the opposition's supply lines, and captured vehicles, armour, and other heavy equipment are not stored nearby. While the FSA continues to wage a guerrilla war in Damascus, it cannot stand toe-to-toe with the Assad military.
The opposite may soon be true in Aleppo. Large-scale defections have occurred in the countryside and suburbs within 20 kilometres (12 miles) of the city. The opposition has won control of a string of towns to the north and west. Supplies, fighters, and heavy equipment is moving from Idlib Province and from Turkey. While fighters inside the city are few, battles relatively scattered, and the regime's military strong, in the next few weeks the Free Syrian Army may have the city surrounded with thousands of fighters.
Meanwhile, all of the border crossings with Iraq and some of those with Turkey have fallen to the FSA. Kurdish towns have been taken by local forces, and Al Bukamal and Deir ez Zor are in danger of falling to the insurgents. The opposition has won significant military victories in and around Homs, there is now heavy fighting in Daraa, and the fighting continues in Damascus. Assad will soon be faced with some stark choices: which cities can he afford to hold on to while still having enough strength to hold his capital? The abandonment of any cities or provinces north of Damascus, such as Homs, Hama, and Idlib) will affect Assad's ability to hold Aleppo.
A scenario. The regime will continue to fight for control of the supply lines that run from Damascus to Homs, Hama, Idlib, and Aleppo. As it does so, it will lose more territory to the north and east of Aleppo. The vice will eventually close on the city, and it will fall to the FSA.
And if Aleppo falls, this war is over. Assad will then lose all of Idlib Province --- which has in effect already happened --- then Hama, then Homs.
In short, unless there is a surprising change in the course of this fight, every indication is that the President Assad cannot win this war.