Facebook on Thursday said it had removed hundreds of pages that originated in Russia for engaging in “coordinated inauthentic behavior” on its site, including a network of accounts that touched on regional weather and sports but actually served as a way for Russian state-owned media to secretly reach social media users.

The tech giant’s latest takedown — announced in an early-morning blog post — included more than 300 pages that primarily targeted regions including Eastern Europe and Central Asia. The pages represented themselves as independent news sites or hubs for information about travel, economics and local politicians, Facebook said. But they each had undisclosed links to employees of Sputnik. The news website is owned by Rossiya Segodnya, the Kremlin’s news agency.

More than 790,000 users followed at least one of the suspended pages, according to Facebook, which operated between October 2013 and January 2019. The pages frequently posted about politically sensitive issues, including anti-NATO sentiment. Researchers at the Atlantic Council’s Digital Forensic Research Lab, which reviewed Facebook’s data, described the campaign as a “systematic, covert attempt” to improve the reach of Russian state-owned media “across more than a dozen countries.”

While the effort did not appear to target the United States, Facebook’s removal of Russian-linked accounts could rekindle fears in Washington that the site and its photo-sharing service, Instagram, remain vulnerable to manipulation by agents of Moscow and other bad actors.

Russian operatives targeted the U.S. presidential election in 2016, seeking to sow social and political unrest online. The disinformation campaign reached hundreds of millions of U.S. users on Facebook and other social media sites, prompting each of those companies to toughen its policies. Facebook has since removed networks of accounts with ties to Russia and other instances of coordinated, inauthentic behavior connected to Iranian state-owned media.

“While we are making progress rooting out this abuse, as we’ve said before, it’s an ongoing challenge because the people responsible are determined and well-funded,” Nathaniel Gleicher, the head of cybersecurity policy at Facebook, wrote in an update Thursday.

Facebook also said it took action against a second set of fake and malicious accounts that originated in Russia and sought specifically to target Ukraine. The company said the accounts — brought to its attention by the U.S. government — had “some technical overlap with Russia-based activity we saw prior to the US midterm elections,” including behaviors linked to the Internet Research Agency.