But the wildly popular, Chinese-owned social media app also walled off Russian users from seeing any posts at all from outside the country, including from Ukraine — effectively creating a second, censored version of its platform. For the tens of millions of Russians on TikTok, the outside world has fallen silent.

TikTok’s block on outside content appears to have effectively purged the app of non-Russian content. But its block on Russian content has proved porous, letting pro-government propaganda slip through. New research from the European nonprofit Tracking Exposed, shared with The Washington Post, shows that videos bearing pro-war hashtags such as “for us” and “Putin top” continued to proliferate on TikTok in Russia for weeks after the block, while previously popular antiwar hashtags all but vanished from the platform.

“In just one month, TikTok went from being considered a serious threat to Putin’s national support for the war to becoming another possible conduit for state propaganda,” said Giulia Giorgi, a researcher at Tracking Exposed, which has been studying the platform’s policies and actions in Russia since the invasion began in February. “Our findings show clearly how TikTok’s actions influenced that trajectory.”