Introduction “ YouTube reflects the duality characterizing all of the major social media companies: It has served as a vital information pipeline to ordinary Russians during the war in Ukraine but in the past enabled Vladimir Putin's propagandists. ” For at least a decade before Vladimir Putin’s invasion of Ukraine in 2022, the Russian ruler relied on one social media platform more than any other to spread disinformation in the West. That platform was YouTube. Over the years, Kremlin-controlled propaganda outlets, spearheaded by RT (formerly Russia Today) and Sputnik News, amassed millions of subscribers and billions of views on YouTube, primarily outside of Russia.3 In 2013, Robert Kyncl, then a YouTube vice president and now its Chief Business Officer, visited an RT studio to celebrate the outlet’s accumulation of one billion views. The executive praised RT for offering viewers “authentic” content rather than “agendas or propaganda.”4 In fact, enabled by YouTube, RT was transmitting a steady stream of Kremlin propaganda. In 2014, RT produced elaborate justifications for Russia’s forcible annexation of Ukraine’s Crimea region and incitement of insurrection in the Donbas area. After RT participated in a Russian information operation interfering with the 2016 U.S. presidential election, American intelligence agencies described the Kremlin-affiliated service as Putin’s “principal international propaganda outlet.”5 Over the years, YouTube has removed some videos from RT channels, and in 2018 it began labeling RT and Sputnik content as governmentfunded. But by then, the Russian disinformation purveyors had established their global YouTube following.6 Even as it was helping RT expand its Western audience, YouTube emerged as the most-visited social media platform in Russia—more popular than VK, the Russian equivalent to Facebook. An estimated 75% of Russians active on the internet now use YouTube. By comparison, 50% use Instagram and just 5%, Twitter.7 Paradoxically, even as YouTube amplified Kremlin disinformation aimed at the West, it offered ordinary Russians an alternative to state-approved news outlets. The information environment in Russia shifted drastically when Putin’s tanks rolled into Ukraine in February 2022. The Kremlin enacted stiff prison terms for war reporting at odds with Moscow’s official line. Foreign journalists in Russia went silent, and many departed. The few independent Russian broadcast and print outlets shut down. Meanwhile, the state media regulator blocked Russian access to Facebook and Instagram and sharply restricted use of Twitter. Amid the methodical censorship, only one major outside source of news remained readily accessible—YouTube.8 Russian viewers could go to the videosharing platform to watch BBC and HOW YOUTUBE SPREADS HARMFUL CONTENT – AND WHAT CAN BE DONE ABOUT IT 3