I've written a few times about Russia's attempts to clamp down on social media and, in particular, the popular messaging app Telegram. At some point last year, Putin decided that having a messaging app in Russia which he couldn't personally control was a problem. The messages there are presumed to be fully accessible to the F.S.B., the state security agency that succeeded the Soviet K.G.B. Now Russia has taken its war against Telegram to the next level. The security service, the F.S.B., said in a statement that it had issued an international warrant to arrest the Telegram founder, Pavel Durov, 41, who is Russian-born.