Russia could block access to Facebook and Twitter if the social media companies fail to fulfil its demand to move data on Russian users to servers located within the country, officials have warned. Alexander Zharov, the head of Roskomnadzor, Russia’s communications watchdog, said the western companies had nine months to bring their operations in line with Russian internet security laws. “They’ve been given time to comply,” he said. A law approved in 2014 by Russia’s president, Vladimir Putin, requires domestic…