Quoting an Arab Times article now offline but available here and here:

Al-Fadhli lives in north of Syria, where he is in control of al-Qaeda. He entices and recruits jihadists from among the European Muslim youths, or from those who embrace Islam. After choosing the youths, he trains them on how to execute terror operations in the western countries, focusing mostly on means of public transportation such as trains and airplanes. His activities were also focused on directing the al-Qaeda elements to execute operations against four main targets, which are Assad’s military, the Free Syrian Army, the ‘Islamic Front’ and ‘Da’esh’. Sources revealed that Al- Fadhli supports ‘Al-Nusra Front’ against ‘Da’esh’, especially after the Al-Nusra leader Abu Mohammad Al-Joulani declared his loyalty to al- Qaeda group in April last year.

The decision taken by Al- Zawahri to support ‘Al-Nusra Front’ to face ‘Da’esh’ was made after Al-Fadhli provided information about what is happening in Syria. Sources stressed that such a decision indicates the confidence al- Qaeda leadership has in Al- Fadhli. It also confirms that Al- Fadhli is the de facto leader of al-Qaeda in Syria, even though it has not been officially announced over fear of exposing him. Al-Zawahri hid the identity of his personal representative in Syria when he announced, “Al-Nusra Front is the official wing of the al-Qaeda in Syria”, which suggested that its leader Al-Joulani is al-Qaeda’s functional leader in Syria. Sources also indicated the dangerous game played by Iran in Syria that is aimed to tarnish the image of the revolution and wipe it out.