Attorneys for Taylor Swift are threatening legal action against the Florida college student who tracks the private jets of celebrities and public figures, including Swift.

Jack Sweeney confirmed to CNN on Tuesday that he received a cease-and-desist letter threatening legal action from attorneys for Swift about the social media accounts he runs that track Swift’s flights. The news was first reported by the Washington Post.

Sweeney is the same person who famously drew ire from billionaire Elon Musk for tracking his jet travels online. Musk, who owns X, disbanded Sweeney’s account “@ElonJet” on the social media platform formerly known as Twitter in December 2022.

Sweeney, who was let back on the X platform, also runs accounts that track the private jet movements of Mark Zuckerberg, Bill Gates, and a spate of other celebrities and public figures. Musk has previously said the accounts pose a “security risk” for him and his family.

Sweeney operates the accounts on several social media platforms using publicly-available flight data from the Federal Aviation Administration as well as flight signals tracked by individual aviation enthusiasts, and often includes estimates of carbon emissions from each flight he tracks in the posts.

The December letter from Swift’s lead attorney on this issue, Katie Morrone of Venable LLP, accuses Sweeney of engaging in “stalking and harassing behavior, including consistently publishing real-time and precise information about our client’s location and future whereabouts to the public on social media.”

The letter claims this poses an “imminent threat to the safety and wellbeing” of Swift. It also accuses Sweeney of disregarding the public safety of others “in exchange for public attention and/or requests for financial gain.”

The letter even references CNN reporting on Musk offering Sweeney $5,000 to delete the Twitter account tracking his jet. (Sweeney refused this offer at the time and asked for $50,000, saying he could use the money to pay for college or perhaps to buy a Tesla).

The letter states that it is a “life-or-death matter” for Swift, who has dealt with stalkers and others who wish her harm since she was a teenager. The letter states that there are “many public cases” of individuals who have come to Swift’s residences, including armed with weapons and ammunition, and “attempted to harm her.” The letter argues that sharing her location information gives these bad actors “a roadmap to carry out their plans.”

If Sweeney continues to publish information tracking Swift’s jet travels, her attorneys add, “She will have no choice but to pursue any and all legal remedies available to her.”

Sweeney told CNN over email that he received the letter from Swift’s attorneys after headlines from some non-profit organizations and media outlets scrutinized the singer’s carbon footprint.

Sweeney also told CNN that he never intended any harm with his actions, noting that he is compiling “public information.”

“I actually think Swift has some good songs,” Sweeney added. Still, he said, “I believe in transparency and public information.” Sweeney also said there is high public interest from Swift’s fans in the accounts, saying she should have “a decent expectation” that her jet will be tracked “whether or not I do it.”

A representative for Taylor Swift declined CNN’s request for comment Tuesday. When asked about evidence that stalkers of Swift had used the jet-tracking accounts run by Sweeney, a spokeswoman for Swift told the Washington Post, “We cannot comment on any ongoing police investigation but can confirm the timing of stalkers suggests a connection. His posts tell you exactly when and where she would be.”

Interest in Swift’s upcoming travels, and specifically whether she will make it back to the U.S. from her overseas tour in time to see her boyfriend Travis Kelce in the Super Bowl, has intensified in recent weeks.

Just last week, the Japanese Embassy in the U.S. tweeted a statement saying that despite the long-haul flight back from Tokyo and a 17-hour time difference, Swift should be able to make it to Las Vegas from Tokyo in time for the big game if she departs Tokyo in the evening after her concert.