Delta Air Lines (DL, Atlanta Hartsfield Jackson) and all other US-based airlines have been banned from operating within the Damascus Flight Information Region, which includes all of Syria, by the US Federal Aviation Administration (FAA) with immediate effect.

In its NOTAM, the FAA said the decision to enact the ban was as a result of the ongoing conflict in the region as well as that in neighbouring Iraq where the militant-backed Islamic State (IS) has declared a self-proclaimed caliphate. The FAA said the IS' possession of anti-aircraft weapons posed a 'significant threat' to civilian traffic operating within Syrian airspace.

"The ongoing armed conflict and volatile security environment in Syria poses a serious potential threat to civil aviation. Armed extremist groups in Syria are known to be equipped with a variety of anti-aircraft weapons which have the capability to threaten civilian aircraft," the NOTAM read. "Opposition groups have successfully shot down Syrian military aircraft using these anti-aircraft weapon systems during the course of the conflict. Opposition elements have previously warned civilian air carriers against providing service to Syria."

A previous NOTAM had strongly advised US operators against flying in that airspace and had required them to contact the FAA before operating over Syria.

At present, no known US airlines operate or have operated over Syrian territory.