Videos and witness accounts suggest that the rebels have seized SA-7 missiles, a Soviet-era weapon, and the later version, the SA-16. They have also shown off training versions of a state-of-the-art Russian-made SA-24, which like its predecessor uses heatseeking guidance systems.

[A] government gunship being [seen] brought down by a missile outside Aleppo.

US veto on supplies of sophisticated, potentially decisive weapons such as shoulder-launched anti-aircraft missiles (widely known as Manpads – an acronym for man-portable air-defence systems) to the rebels.

The US veto was motivated principally by the fear of such a weapon falling into the hands of a jihadist group that would then use it to bring down a civilian airliner, as al-Qaida tried to do with an Israeli plane in Mombasa in December 2002.

So far, there is no evidence that any of the ground-to-air missiles used to date have come from outside Syria, according to Peter Bouckaert. Emergencies director for Human Rights Watch.