(CNN) -- More than 90% of the Internet access in Syria was shut down on Thursday, according to the Internet monitoring group Renesys. It was not clear who was behind the latest event, but the government has intermittently cut off Internet access several times in the past two years. Opposition activists often transmit updates about the civil war in reports and images on the Web. Syria has shut down the Internet in the past, said U.S. Ambassador to Syria Robert Ford. Ford added that the United States has given "a thousand pieces of non-lethal equipment -- largely communications gear" to help opposition activists get around blocks to the Internet.
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NEW: More than 90% Internet access blocked, Renesys says
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NEW: U.S. Ambassador to Syria says communications gear given to Syrians to get around blocks
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Rebels claim to have shot down three government aircraft in 24 hours
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Turkey formally requests Patriot missiles from NATO
A letter to @placeholder included the "formal request" that the alliance send "air defense elements," according to a Turkish government statement that cited "the threats and risks posed by the continuing crisis in Syria to our national security."