Taylor Swift’s attorneys have threatened legal action against a Florida college student who runs social media accounts tracking the flights of her and other celebrities’ private jets.

Jack Sweeney, a junior at the University of Central Florida, has for years run accounts that log the takeoffs and landings of planes and helicopters owned by hundreds of billionaires, politicians, Russian oligarchs and other public figures, along with estimates of their planet-warming emissions. The accounts use publicly available data from the Federal Aviation Administration and volunteer hobbyists who can track the aircraft via the signals they broadcast.

Sweeney’s accounts fueled a free-speech debate in late 2022 when X, formerly Twitter, banned Sweeney for sharing what the platform’s owner, Elon Musk, said were his “assassination coordinates.” The accounts don’t say who travels on the aircraft or where they go once the planes land.

In December, Swift’s attorney at the Washington law firm Venable wrote Sweeney a cease-and-desist letter saying Swift would “have no choice but to pursue any and all legal remedies” if he did not stop his “stalking and harassing behavior.”