The legal team of pop star Taylor Swift, Washington, D.C., is threatening legal action against a student who tracked her use of her private jet on social media.

According to the Washington Post, the singer’s lawyers have sent a letter to Jack Sweeney, a University of Central Florida student who runs various social media accounts that track the private jet use of public figures between them and Swift. It is noted that in the past he had caused the wrath of billionaire Elon Musk.

For years, the student manages these accounts and measures the carbon footprint. Sweeney’s coverage, which uses publicly available data from the Federal Aviation Administration (FAA) and signals emitted by aircraft, has been widely praised and earned him a Forbes 30 under 30 award, the Guardian reports.

But in December, the star’s lawyers accused him of “stalking and harassing conduct” for monitoring her aircraft activity.

“While this may be a game to you or an avenue you hope will bring you wealth or fame, it is a matter of life and death for our client,” Katie Wright Morrone wrote in the letter, according to the Post.

Swift fans for their part in their social media posts they decried the letter from Swift’s legal team and called it “harsh”.