The Russian government has filed a lawsuit seeking to restrict access to a popular messaging app after its owners refused to give the Kremlin access to its users’ secret messages. Much like WhatsApp, Telegram, which has around 200 million users and is popular in former Soviet countries, allows users to send encrypted messages that can’t be read by third parties—including government security services. Russia’s security service, the FSB, has said it needs access to the messages to be able to prevent terrorist attacks and for other national-security work, but Telegram officials have vowed to protect users’ privacy. Telegram founder Pavel Durov said in March: “Threats to block Telegram unless it gives up private data of its users will not bear fruit. Telegram will stand for freedom and privacy.” Meanwhile, Russia has asked Facebook to explain why it removed dozens of Russian accounts associated with a known troll farm, claiming the social media company has an “unfriendly policy toward Russian users.”