A California firm that makes internet-blocking equipment has acknowledged that the Syrian government has been using at least 13 of its devices to suppress dissent and block access to the internet despite a U.S. trade embargo. The company, Blue Coat Systems, claims it does not know how its devices got to Syria. Since 2004, the United States has prohibited the export, without a special license, of most U.S. goods and services to Syria. Blue Coat Systems’ technology has also been used by several U.S. allies for censorship and surveillance, including Bahrain, Saudi Arabia and Qatar.