MOSCOW—A Russian court on Tuesday said it had fined U.S. social media companies Facebook and Twitter for failing to delete content that Moscow deems illegal, part of a wider crackdown by Russia on the internet and Big Tech. The Tagansky district court said Facebook had been handed five fines totaling 21 million roubles ($287,850). Twitter received two fines of a total of 5 million roubles ($68,550), it said. Popular messaging app Telegram had been fined 9 million roubles ($123,390), the court said. Facebook, Twitter, and Telegram had no immediate comment. Moscow’s actions to strengthen its control of the internet have included a push to require foreign internet companies to open fully-fledged offices in Russia and to store Russians’ personal data on its territory. On Tuesday, the government published plans to impose new taxes on foreign-owned digital services, a move aimed at supporting its domestic tech sector. In March, state communications …