There's been a number of reports that Internet connectivity to Syria has been broken or disabled and there is no official word on what has caused this.

Google's Transparency Report page [1] displays the drop off and a more comprehensive report is on Umbrella labs blog [2]

[1]  http://www.google.com/transparencyreport/traffic/#expand=SY

[2] http://labs.umbrella.com/2013/05/07/breaking-news-traffic-from-syria-disappears-from-internet/   

Chris Mohan --- Internet Storm Center Handler on Duty