The report said on Friday that Musk filed counterclaims against Twitter's lawsuit, but the details are not viewable to the public as it was made confidentially. However, claims may be available sometime within the next week.
The trial for Twitter's lawsuit against Musk is set to start on October 17.
Musk has argued the volume of fake accounts on Twitter is higher than the 5% the company had reported as a basis for the deal he had agreed to in April.
The Journal reported that Musk's response also included a Warren Buffet quote: “Only when the tide goes out do you discover who’s been swimming naked." It's speculated the note is in reference to Musk's claims of bot Twitter accounts.
The takeover was approved by Twitter’s Board of Directors in June, but Musk attempted to terminate the deal in early July, prompting Twitter to file a lawsuit to compel him to follow through on his purchase.