London Guardian 
December 24, 2012
Russian military advisers are manning some of Syria’s more sophisticated air defences – something that would complicate any future US-led intervention, the Guardian has learned.
The advisers have been deployed with new surface-to-air systems and upgrades of old systems, which Moscow has supplied to the Assad regime since the Syrian revolution broke out 21 months ago.
The depth and complexity of Syria’s anti-aircraft defences mean that any direct western campaign, in support of a no-fly zone or in the form of punitive air strikes against the leadership, would be costly, protracted and risky. The possibility of Russian military casualties in such a campaign could have unpredictable geopolitical consequences.
Meanwhile, near-daily atrocities have kept western governments under pressure to act. A Syrian government air strike on a town near the central city of Hama on Sunday killed dozens of civilians queueing for bread , according to human rights activists.