"MANPADS were developed in the 1940s to provide military ground forces with protection from enemy aircraft. They have received a great deal of attention, partly because armed groups have used them against commercial airliners. These missiles, affordable and widely available through a variety of sources, have been used successfully over the past three decades both in military conflicts, as well as by terrorist organizations.
Twenty-five countries, including the United Kingdom, the United States, Sweden and Russia produce man-portable air defense systems. Possession, export, and trafficking in such weapons is officially tightly controlled, due to the threat they pose to civil aviation, although such efforts have not always been successful.
The missiles are about 1.5 to 1.8 m (5 to 6 ft) in length and weigh about 17 to 18 kg (37 to 40 lb), depending on the model. Shoulder-fired SAMs generally have a target detection range of about 10 km (6 mi) and an engagement range of about 6 km (4 mi), so aircraft flying at 6,100 metres (20,000 ft) or higher are relatively safe. However, the FIM-92 Stinger (1996 version) has a range of 26,000 feet (7,900 m). " wiki on MANPADS
It appears that US +NATO frustration with Russian unwillingness to surrender Syria to the jihadis will express itself in US + NATO sponsored Gulf Arab purchase of MANPADS for the jihadis in Syria. 26 countries make some variation on the theme of these weapons systems. They vary widely in capability but are readily available through grey and black arms merchants or through white market purchases by states. They are not hard to buy one way or another.
A major disincentive for provision of these weapons in the past was the threat these weapons pose to airliners near destination airports. It should be expected that some of the MANPADS provided to jihadi groups in Syria will be re-exported to their comrades abroad. They would be a particular threat to Israeli airliners.
Would the introduction of such weapons to the Syria Civil War on the rebel side be a game changer? I doubt but do not know enough about the particular weapons available to have a valid opinion. pl