"As head al Qaeda facilitator in Iran, al Suri is responsible for overseeing al Qaeda efforts to transfer experienced operatives and leaders from Pakistan to Syria, organizing and maintaining routes by which new recruits can travel to Syria via Turkey and assisting in the movement of al Qaeda external operatives to the West," an unnamed State Department official told Al Jazeera.
Al Jazeera notes that al Suri, a native Syrian from Aleppo, has been living in Iran since at least 2005 with the government's consent.
That arrangement is puzzling, given Iran's staunch backing of the regime of Syrian President Bashar al-Assad.
As Thomas Joscelyn of the Long War Journal put it:
It is not clear why the Iranian government would allow al Suri to act as a facilitator for al Qaeda's operations inside Syria. Al Qaeda and Iran are on opposite sides of the Syrian war.
U.S. government
A former C.I.A. officer told Dexter Filkins of The New Yorker that Suleimani is the "most powerful operative in the Middle East today."
The 56-year-old is personally handling Iran's extensive contributions to the Assad regime and has allowed al Qaeda operatives a degree of freedom in Iran since several arrived after 9/11.
Also of note is the potential role of Turkey, given that many of the extremists have benefited from lax border security to pass from Turkey into Syria.
Al Monitor reports that about a month ago, a high-ranking delegation from Iran visited met high-ranking Turkish officials, including Prime Minister Recep Tayyip Erdogan, in Ankara and "there was agreement on exchanging information and coordinating closely on the situation in Syria."
The al Qaeda-linked groups in Syria, Jabhat al-Nusra and Islamic State of Iraq and al-Sham (ISIS), have also been selling oil to the Assad regime while reportedly receiving money and recruits from al-Suri.
ISIS, the most extreme rebel faction in Syria, is dominated by foreigners. Activists claim that one ISIS leader who was captured in Aleppo held an Iranian passport.
Here's al Jazeera's report: