The head of the Aleppo branch of the Revolutionary Military Police, Abu Ahmed Rahman, comes from Liwa al-Tawhid, the largest rebel force in Aleppo. Ostensibly al-Tawhid has pledged its support for the U.S.-recognized Syrian National Coalition, but its role in the Authority alongside Ahrar al-Sham and Jabhat al-Nusra shows an alliance with more radical groups.
As Rahman sat at a large desk on the ground floor, people rushed in and out, asking him to stamp and sign documents. He said that the worst problem the police had encountered so far was with Ghurabaa al-Sham, who had clashed with a sub-division of Liwa al-Tahwid for control of Aleppo's industrial city, a complex of factories and office blocks sprawling over 4,000 hectares on the north-east outskirts of the city.
"Ghurabaa al-Sham fighters were annoying people, looting," he said. The industrial area offered plenty of plunder. Residents of Aleppo said rebels found machinery and equipment in the factories that could be sold in Turkey.
Rahman said the Authority summoned Ghurabaa al-Sham to a hearing but they didn't show up. "Then all the brigades went to get them. Jabhat al-Nusra, Ahrar al-Sham and other rebel units," he said.
Abu Baraa, an employee at the Authority, said: "We gathered a lot of people with guns and everything. We went to the industrial city and we arrested everyone who was there. Then we did the interrogation. Those who did not steal were set free, and the others were put in prison.
"Before this Sharia Authority, every brigade did whatever it wanted. Now they have to ask for everything. We are in charge now, God willing. We are the supervisors. If you do something wrong, you will be punished."
A POWER STRUGGLE
Members of Ghurabaa al-Sham gave a different version of events and have a different world view. "Why is the Sharia Authority allowed to control us? We didn't elect them," said Abdul-Fatah al-Sakhouri, who works in the media center for Ghurabaa al-Sham, an old taxi station in Aleppo where he and some other fighters upload videos of battles against the Syrian army onto YouTube.
Al-Sakhouri, previously a mathematics teacher, said the head of the Ghurabaa al-Sham unit in the industrial city had gone to the Authority to sort out the dispute. "Commander Hassan Jazera was there for three hours and then left. It shows that they didn't arrest him and there were no real charges against us," he said.
The dispute, Ghurabaa al-Sham fighters said, was really about power. They said their brigade, made up of fighters ranging from Islamists to secularists but all in favor of a civilian state, was not part of the Islamist alliance formed between Jabhat al-Nusra, Ahrar al-Sham and Liwa al-Tawhid.
Another member of Ghurbaa al-Sham, who called himself Omar, said the Islamist alliance wanted to weaken his group because it disagrees with Islamist ideology and seeks democracy.
Illustrating his fear of Islamist cultural restrictions, Omar said he was a fan of the American heavy metal band Metallica and pulled out a mobile phone to show a Metallica music video. The 24-year-old said Syrian businessmen once promised millions of dollars to bring Metallica to Aleppo but, in the end, the government rejected the plan.
"Jabhat al-Nusra wouldn't want this either," he said.
So far the Islamist groups have been the ones to attract outside support, mostly from private Sunni Muslim backers in
Saudi Arabia
, according to fighters in Syria.
With the help of battle-hardened Sunni Iraqis, these groups have been able to gain recruits. "They had military capabilities. They are actually organized and have command and control," said Zelin of the Washington Institute for Near East Policy.
As moderate rebel groups dithered, so did their backers outside the country. Bickering among the political opposition, a collection of political exiles who have spent many years outside Syria, also presented a problem for the United States about whether there would be a coherent transition to a new government if Assad fell.
But most importantly, Western powers fear that if weapons are delivered to Syrian rebels, there would be few guarantees they would not end up with radical Islamist groups, such as Jabhat al-Nusra, who might one day use them against Western interests.
The moderates are losing ground. In many parts of rebel-held Aleppo, the red, black and green revolutionary flag which represents more moderate elements has been replaced with the black Islamic flag. Small shops selling black headbands, conservative clothing and black balaclavas have popped up around the city and their business is booming.
Reuters met several Islamist fighters who had left more moderate rebel brigades for hardline groups. One member of Ahrar al-Sham, who would only speak on condition of anonymity, said: "I used to be with the Free Syrian Army but they were always thinking about what they wanted to do in future. I wanted to fight oppression now."