As Mr. Putin has waged war on Ukraine, a digital barricade went up between Russia and the world. Both Russian authorities and multinational internet companies built the wall with breathtaking speed. And the moves have ruptured an open internet that was once seen as helping to integrate Russia into the global community.

TikTok and Netflix are suspending their services in the country. Facebook has been blocked. Twitter has been partly blocked, and YouTube’s future is in doubt. Apple, Samsung, Microsoft, Oracle, Cisco and others have pulled back or withdrawn entirely from Russia. Even online video games like Minecraft are no longer available.

The actions have turned Russia into a walled-off digital state akin to China and Iran, which tightly control the internet and censor foreign websites and dissent. China’s internet and the Western internet have become almost completely separate over the years, with few overlapping services and little direct communication. In Iran, the authorities have used internet blackouts during protests…

“The vision of a free and open internet that runs all over the world doesn’t really exist anymore,” said Brian Fishman, a senior fellow at the New America think tank and former director of counterterrorism policy at Facebook. “Now the internet is lumpy. It has choke points.”