Fireeye is reporting that a hacking group called Ghostwriter broke into the content management systems of Eastern European news sites to plant fake stories.

From a Wired story:

The propagandists have created and disseminated disinformation since at least March 2017, with a focus on undermining NATO and the US troops in Poland and the Baltics; they've posted fake content on everything from social media to pro-Russian news websites. In some cases, FireEye says, Ghostwriter has deployed a bolder tactic: hacking the content management systems of news websites to post their own stories. They then disseminate their literal fake news with spoofed emails, social media, and even op-eds the propagandists write on other sites that accept user-generated content.

That hacking campaign, targeting media sites from Poland to Lithuania, has spread false stories about US military aggression, NATO soldiers spreading coronavirus, NATO planning a full-on invasion of Belarus, and more.