In this image taken from video obtained from the Ugarit News, which has been authenticated based on its contents and other AP reporting, Free Syrian Army fighters capture a helicopter at the Marj al-Sultan military air base in Damascus, Syria, on Wednesday, Nov. 28, 2012. (AP Photo/Ugarit News via AP video) Enlargephoto

In this image taken from video obtained from the Ugarit News, which has been authenticated based on its contents and other AP reporting, Free Syrian Army fighters capture a helicopter at the Marj al-Sultan military air base in Damascus, Syria, on Wednesday, Nov. 28, 2012. (AP Photo/Ugarit News via AP video)

2 US-based Internet-monitoring companies say Syria has shut off Internet nationwide.

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