State communications regulator Roskomnadzor has begun blocking access to Telegram, seeking to bar Russians from using the popular app whose self-exiled CEO has defied demands to let the Federal Security Service (FSB) read users' messages.
Roskomnadzor said in a statement on April 16 that it had notified Internet providers that they must "restrict access" to Telegram as the result of an April 13 court ruling in favor of the regulator.
Telegram CEO Pavel Durov swiftly denounced the Roskomnadzor order, saying that "the quality of life of 15 million Russians will worsen" as a result.
"We consider the decision to block [Telegram] unconstitutional and will continue to stand up for the right of Russians to confidential correspondence," Durov wrote on the social network VKontakte, adding a clenched-fist emoji.
In central Moscow, supporters of Telegram threw paper airplanes at the headquarters of the FSB on Lubyanka Square. The OVD-Info website that monitors law enforcement activity in Russia said 12 participants in the protest action were detained.
Russia's campaign to block Telegram has deepened concerns that the government is seeking to close avenues for dissent as President Vladimir Putin heads into a new six-year term.
Amnesty International said on April 12 that blocking Telegram, which has been used by senior government officials as well as Kremlin critics, would be "the latest in a series of attacks on online freedom of expression" in Russia.
The April 13 court decision followed a monthslong standoff between Telegram and the FSB, which demanded the encryption keys that would give it access to users' messages. Durov refused, saying the request was unconstitutional.
"Privacy is not for sale, and human rights should not be compromised out of fear or greed," Durov, who left Russia in 2014, said on Telegram after the ruling.
Clients of leading Internet providers in Russia -- Beeline, Megafon, Yota, MTS, and Tele2 -- said on April 16 they were not able to access Telegram and had to use virtual private networks (VPNs) to avoid the blockage.
Roskomnadzor chief Aleksandr Zharov said that "measures against the tools to avoid the blockage of Telegram will be undertaken in accordance to the law and on request by law enforcement."
Zharov added that the media regulator would officially request that U.S.-based Internet giant Apple's App Store and Alphabet's Google Play remove Telegram messenger app from their sites.
Pavel Chikov, a rights activist and attorney who represents Telegram, said on April 16 that Telegram's lawyers had managed to postpone the blockage by several months, which he said helped to raise awareness about the situation around the world.
"We consider the first stage of our work accomplished, but there are more important stages ahead," Chikhov wrote on Telegram, adding that law enforcement authorities "have no chance to defeat progress."
Durov first revealed the FSB demand in September 2017, saying the intelligence agency had notified him that Telegram was in violation of a controversial antiterrorism law requiring companies to provide access to encrypted communications they facilitate.
Writing on VKontakte on April 16, Durov said that blocking Telegram would not reduce the "terrorist threat to Russia" because "extremists will continue to use digital communications channels."
He added: "Russia's national security will diminish because some Russians' personal data will move from a platform that is neutral to Russia to WhatsApp and Facebook, which can be monitored from the United States."
Human Rights Watch has said that antiencryption provisions in the so-called Yarovaya laws, adopted in 2016, would "endanger activists and journalists who rely on encrypted messaging applications to communicate securely."
Durov fought the demand, but Russian courts have ruled against Telegram at every juncture.
When the Supreme Court threw out an appeal on March 20, Roskomnadzor ordered Telegram to provide the FSB with the encryption keys within 15 days.
Telegram did not comply and the regulator filed suit, leading to the April 13 ruling.
Durov, 33, announced in 2014 that he had left Russia after he was forced to sell his stake in another popular social network, VKontakte, amid pressure from authorities.
Telegram has attracted more than 200 million users worldwide since it was launched by Durov and his brother in 2013.
It allows users to communicate via encrypted messages that cannot be read by others outside the exchanges -- including government authorities.
Russian activists and government critics have used Telegram and other social media to spread the word about antigovernment demonstrations and to publicize corruption allegations against Putin, a former FSB chief and Soviet KGB officer, and his allies.
Putin's spokeman, Dmitry Peskov, said on April 16 that Russians should not seek ways around the blockage, apparently referring to the prospect that users will seek to retain access via virtual private networks (VPNs).
People should not "play hide-and-seek" with the authorities, Peskov told journalists, adding that the measures to restrict access to Telegram "will be implemented."
The Kremlin had been using Telegram to coordinate timings of frequent phone-in news conferences with Peskov, and many government officials have used it to communicate with the media.
Peskov said on April 13 that the Kremlin will find another messaging service to use in place of Telegram.