On Tuesday night, former Fox host Tucker Carlson launched the first installment of his new social media “show” Tucker on Twitter. According to a letter obtained by Axios, the network sent Carlson a letter claiming the show put him “​​in breach” of his contract with Fox.

“In connection with such breach and pursuant to the Agreement, Fox expressly reserves all rights and remedies which are available to it at law or equity,” read the letter.

In response to Fox, Carlson’s lawyer, Bryan Freedman, told Axios that “Fox defends its very existence on freedom of speech grounds. Now they want to take Tucker Carlson’s right to speak freely away from him because he took to social media to share his thoughts on current events.”

While Carlson was fired from the network in April, his contract with Fox would have seen him collect payment from the network through 2025 if he refrained from creating content that would compete with Fox’s own programming.

Prior to this confrontation, Carlson had already attempted to render the contract null, accusing Fox in May of having breached their agreement, and committing fraud against him. A letter from Carlson’s lawyer to executives at Fox alleged that “Rupert Murdoch himself” reneged on promises made to Carlson, including a commitment to not leak his private communications or use them to “take any adverse employment action against him.”

The two parties are prepared for a hellish confrontation. As previously reported by Rolling Stone, Fox News executives kept a file of potentially damaging dirt from Carlson’s years at the network that they are prepared to weaponize should he step out of line. Despite the threat of a public showdown with his former employer, Carlson has given every indication that he’s not going down without a fight.

A network spokesperson denied the existence of the file on Carlson. “This is patently absurd and categorically false,” the spokesperson said in a statement to Rolling Stone. “We thank Tucker for his service to the network as a host, and prior to that, as a contributor.”