The Russian government has blacklisted the California-based Wayback Machine, a comprehensive archive of the Internet, over an Islamist video available on the website.
The video, called "The Clang of Swords," by the notorious terrorist group Islamic State, was declared extremist by a court in Russia's southern Stavropol region in July.
The state communications watchdog Roskomnadzor said on its website Friday that it had found 400 online copies of the video and requested their removal.
A handful of sites, including Wayback Machine's domain Archive.org, did not comply, leading to their blacklisting.
Though only a few pages were deemed illegal, Archive.org was blacklisted in its entirety because the state bans most sites by their IP address, which is shared by all the site's pages.
About 95 percent of 74,000 websites banned in Russia have no illegal content and are collateral damage from flawed blacklisting mechanisms, according to the independent Internet freedom watchdog Rublacklist.net.
The Wayback Machine, active since the mid-1990s, is a nonprofit organization that preserves content published online. It contained 432 billion webpages as of last month.