Lack of unity
Although many rebel units fight under the banner of the Free Syrian Army, their commands are localised and poorly coordinated, Najjar said.
"One of the biggest factors delaying the revolution is the lack of unity among the rebels," he said. "Unfortunately, it is only when their back is up against the wall that they start to realise they should (unite)."
Syria's uprising has evolved into an all-out civil war with sectarian overtones, pitting the mainly Sunni rebels against security forces dominated by Assad's minority Alawite sect, an offshoot of Shi'ite Islam. Assad is backed by Shi'ite-led Iran and opposed by most Arab states, which are ruled by Sunnis.
"This is not just about the fall of Assad. This is about the Sunni Muslims of Syria taking back their country and pushing out the minority that have been oppressing them for generations now," Najjar said.
The presence of foreign fighters is a sensitive issue for Syria's rebels. Assad's government has taken to referring to the rebels as "Gulf-Turkish forces", accusing the Sunni-led Arab Gulf states and Turkey of arming, funding and leading them.
Harati's unit is known as the Umma Brigade, referring to the global community of Muslims. Najjar said thousands more Sunni fighters from the Arab world were gathering in neighbouring countries prepared to join the cause.
Harati is reluctant to enlist them because he does not want his cause tarnished by the perception that foreign Islamists are linked to al Qaeda, Najjar said, but he said that many of the foreigners were making their way to Syria on their own.
The Umma Brigade's Facebook page shows a picture of Najjar aiming his rifle in what looks like an open field. In another he is posing with Harati and rebels. A YouTube video shows Harati leading an attack on a checkpoint in Maarat al-Numan in Syria.
Najjar said militancy would spread across the region as long as the West does not do more to hasten the downfall of Assad.
"The Western governments are bringing this upon themselves. The longer they leave this door open for this torture and this massacre to carry on, the more young men will drop what they have in this life and search for the afterlife," Najjar said.
"If the West and other countries do not move fast it will no longer be just guys like me - normal everyday guys that might do anything from have a cigarette to go out on the town - it will be the real extreme guys who will take it to another level."