On the fourth anniversary of the Syrian War, Al Jazeera is out with a new documentary that explores why young, Western Muslims feel increasingly compelled to join the fight and also looks at the ideological divide between al-Qaeda’s Syrian arm, al-Nusra and ISIS. For those interested in a first-hand account from those on the ground, the full video is below, along with commentary from the filmmaker, Nagieb Khaja. Via Al Jazeera: In May 2014, I met a group of foreign fighters in northern Syria who introduced me to members of Jabhat al-Nusra, the local al-Qaeda franchise. I immediately began to negotiate access to film with them. Nusra is one of the most powerful, and certainly the most secretive rebel group in Syria. It shares its roots with ISIL. Key members of both groups fought in the brutal Iraqi insurgency of the 2000's, and ISIL and Nusra were initially close allies, fighting under the al-Qaeda banner. But then in mid-2013, a violent conflict over territory and ideology erupted between the two groups. This local dispute has huge implications for global security, with different jihadist groups around the world pledging allegiance either to al-Qaeda or ISIL. The footage I shot with Nusra provides a fascinating insight into al-Qaeda's vision for the future of Syria, and its strategy for beating ISIL in the battle for hearts and minds in the region and beyond… Some analysts believe that Jabhat al-Nusra and ISIL are essentially the same, but my experience on the ground, and my conversations with Nusra members, from foot-soldiers to those in leadership positions, convinced me that there are profound differences between them. Both ISIL and Nusra subscribe to a fundamental version of Islamic law, but it is in the interpretation and implementation that they vary… When the US began targeting ISIL with airstrikes in September 2014 they also hit Nusra units. The US denied attacking Jabhat al-Nusra, however, claiming they had only hit the so-called Khorasan Group - an al-Qaeda cell which the White House alleged was dedicated to planning attacks on US soil. Abu Sulayman refused to comment on this, however, citing security reasons. Whatever the truth about the Khorasan Group, immediately after the strikes, Nusra moved against the US' last remaining allies in region - two relatively secular rebel groups which the US has armed and trained, the Syrian Revolutionary Front and Harakat Hazm. The Syrian Revolutionary Front was quickly defeated and expelled from Syria, and just a few days ago Nusra declared victory over Harakat Hazm, taking over their territory and seizing their US supplied weapons. It is yet another setback for US strategy in the region. Nusra have further consolidated their hold over northwest Syria, and plan to be there for the long-term.