A video released by a Syrian opposition group on 3 September shows a 9K37 Buk-M2E (SA-17 'Grizzly') surface-to-air missile (SAM) transporter-erector launcher and radar (TELAR) vehicle moving at Al-Mezzah Air Base, near Damascus.
Russia delivered an unknown number of the medium-range SAM systems to Syria in 2010-12 and one was subsequently seen in footage of a military exercise that was aired by state television in 2012.
A video released by an opposition group in May showed a TELAR on the back of a transporter that was purportedly destined for Al-Mezzah Air Base.
The more recent video confirms that a Buk-M2E TELAR was deployed at Al-Mezzah because a comparison with satellite imagery shows it was filmed from the northeast, presumably from a multi-storey building outside the perimeter.
The TELAR is typically accompanied by other launcher vehicles that do not have their own target engagement radars, as well as command post and target acquisition radar vehicles, although none of these can be seen in the video.
Almaz-Antey, the Buk-M2E's manufacturer, claims the system is capable of destroying cruise missiles, raising the possibility that the Syrian military will use it in an attempt to defend itself against the likelihood of US military action.
Alternatively, the TELAR may have been seen moving at Al-Mezzah because its battery is being relocated to increase its chances of surviving any US attack.