[Guardian]
Russian military presence in Syria poses challenge to US-led intervention
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. http://www.guardian.co.uk/world/2012/dec/23/syria-crisis-russian-military-presence