Former White House communications aide and new member of the Trump White House tell-all book club Cliff Sims is suing President Trump for his attempts to enforce a nondisclosure agreement signed by Sims—and many others—when he worked for the Trump presidential campaign. Sims, the New York Times reports, is suing Trump in his official capacity as president, saying that Trump is using his campaign apparatus to seek retribution against federal employees, like Sims, who are writing and disclosing information about their time working for the federal government, not as an employee of the campaign.

The suit was prompted by the Trump campaign organization’s filing of an arbitration claim against Sims last week following the publication of Team of Vipers, which, from the title, you can tell was not a fawning account of Sims’ 500 days in the West Wing. The suit, filed in D.C., says Trump “is seeking to impose civil liability against Mr. Sims through application of NDAs that apply to information Mr. Sims learned solely during his federal service.” This is not the first book to be written about Trump, and this is not the first instance where Trump has initiated legal action, a move that publishers certainly relish given the publicity that comes with the legal proceedings and the general legal sense that the NDA is largely unenforceable.

“The suit notes that Mr. Trump appears to be selective in enforcing the nondisclosure agreements [as] he attempted to enforce it against Omarosa Manigault Newman, whose book also infuriated him, but he did not do so against Sean Spicer, or Corey Lewandowski and David Bossie, three former aides who wrote books that the president found flattering and therefore not objectionable,” the Times reports. “Mr. Trump has repeatedly used the threat of arbitration over the nondisclosure agreements to silence former aides. It has not always been successful: One former aide, Sam Nunberg, succeeded in a counterclaim when Mr. Trump tried to enforce the agreement during the 2016 campaign, and the dispute was settled.”

Trump, for his part, has been very Trumpy about the whole thing, directing diss tweets Sims’ way. “A low level staffer that I hardly knew named Cliff Sims wrote yet another boring book based on made up stories and fiction,” Trump tweeted at one point. “He pretended to be an insider when in fact he was nothing more than a gofer.”