HONG KONG—U.S. technology titans face a looming test of their free-speech credentials in Hong Kong as China’s new national-security law for the city demands local authorities take measures to supervise and regulate its uncensored internet.
Facebook Inc. and its Instagram service, Twitter Inc. and YouTube, a unit of Alphabet Inc.’s Google, operate freely in the city even as they have been shut out or opted out of the mainland’s tightly controlled internet, which uses the “Great Firewall” to censor information.
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