VICE News filmmaker Medyan Dairieh gains exclusive access to the Syrian branch of al Qaeda, al Nusra, a jihadist group fighting against President Bashar al-Assad's forces and the Islamic State (IS).

Spending more than a month with al Nusra and exploring their expanding territory, Dairieh meets the highest-ranking members of the organization, who reveal their identity on screen for the first time and discuss their military doctrine.

Al Nusra, which swore allegiance to al Qaeda two years ago and is now emerging as a powerful force to rival IS in Syria, has seized several strategic towns in the northwestern province of Idlib. While it supplies water, electricity, and food to the local population, a school run by al Nusra is also grooming young boys to become the next generation of al Qaeda and preparing them for jihad.

VICE News also secures exclusive access to the front lines of the battle for Abu al-Duhur airport in Idlib, a major airbase held by Assad's forces, besieged by al Nusra for two years. Aided by dust storms during the attack, the airport was the last remaining government stronghold in the region. Dozens of government soldiers were subsequently executed, according to the monitoring group Syrian Observatory for Human Rights.

In this excerpt from 'Inside the Battle: Al Nusra-Al Qaeda in Syria,' VICE News follows al Nusra fighters as they launch assaults on the Abu al-Duhur airport, while dodging sniper fire, mines, and President Assad's warplanes.