The billionaire boys are still beefing. The latest jab in a legal slap-fight between Amazon, founded by Jeff Bezos, and SpaceX, founded by Elon Musk, has landed in the form of a letter from Amazon to the Federal Communications Commission. “With a sigh,” Amazon calls Musk out directly in the letter, accusing his companies of believing that “rules are for other people.” The tech giant also accused SpaceX of relying on a “familiar” set of plays: “concede nothing, ignore rules whenever possible, and when all else fails, malign those that invoke them.”

The letter comes roughly a week after SpaceX’s response to an initial Amazon complaint to the FCC over Musk’s plans to expand the second generation of Starlink, a project seeking to provide global satellite Internet access. SpaceX’s letter observed that the Amazon lawsuits have “become a bigger bottleneck than the technology” in their space race. (Bezos has his own satellite broadband company in the form of Kuiper Systems.)

Musk, for his part, has delighted in responding to the saga on Twitter. When Amazon first urged the FCC to deny SpaceX permission to expand Starlink in August, Musk tweeted, “Turns out Besos [sic] retired in order to pursue a full-time job filing lawsuits against SpaceX.” Bezos-owned companies, including Amazon and spaceflight enterprise Blue Origin, have filed lawsuits against SpaceX just over every fortnight this year.