Ben Gilbert describes himself on Bluesky, the social media app, as an “economist, lit and guitar nerd, rugby fan, owner of excessive pets.” A professor at the Colorado School of Mines, he rarely posts, but when he does, the subjects reflect his expertise in natural resources.

So it was odd when a video purporting to be a news report appeared on his account last month, blaming France’s financial and political support for Ukraine for police staff shortages at home.

Without his knowledge, Mr. Gilbert said, he had fallen victim to Russia’s latest tactic to try to spread its propaganda in the West.

His account, like hundreds of others on Bluesky, had been hijacked and used to post fake news articles, according to the company and researchers at Clemson University working with a collective of internet monitors who track Russian influence operations and call themselves the dTeam.