AP
Telegram, which was created by Pavel Durov, the same founder of Russia's most popular social network, posted a message on its site Wednesday addressing the move.
"We were disturbed to learn that Telegram's public channels were being used by ISIS to spread their propaganda," it read. "As a result, this week alone we blocked 78 ISIS-related channels across 12 languages."
This is a surprising reversal for Telegram, since its founder Durov had mocked the idea that ISIS should be banned from Telegram just days prior, as The Washington Post points out.
On his Russian social network VKontakte, Durov wrote, "I propose banning words, there's evidence that they're being used by terrorists to communicate." And in a Facebook post, he said "I think the French government is as responsible as ISIS [for the Friday attacks in Paris]."
At a TechCrunch panel in September, Durov defended the idea that bad people, including terrorists, could use Telegram's highly secure messaging platform.
"If you look at ISIS, yes, there's a war going on in the Middle East," he said. "Ultimately, ISIS will find a way to communicate with its cells, and if any means doesn't feel secure to them, they'll [find something else]. We shouldn't feel guilty about it. We're still doing the right thing, protecting our users' privacy."
Around that same time, Telegram's newly-added public broadcasting feature became a favorite method for ISIS to share news or military victories in hopes of inspiring followers.
And now, even as Telegram blocks ISIS channels left and right, new ones have managed to re-emerge on the network, according to Reuters. It's apparently as easy as changing or adding a letter or number to the original account name, and broadcasting it online for people to join.
Telegram insists this move to rid ISIS from its network isn't to block free speech. "While we do block terrorist bots and channels, we will not block anybody who peacefully expresses alternative opinions," Telegram said on its website.
Over the last few days, ISIS had been using Telegram to share "instructions" in both Arabic and English on how to avoid getting hacked. That's because over the weekend, the online hacking collective Anonymous declared "war" on ISIS after Friday's Paris attacks, helping Twitter shut down thousands of pro-ISIS accounts and leaking personal information about ISIS supporters online.
But there is some sign that this online movement against ISIS is translating to the real world. Reuters reported on Wednesday that Iran has already arrested administrators from more than 20 different Telegram channels this week for spreading "immoral" content.