The White House has formally issued a warning to prevent John Bolton from  publishing his new book The Room Where It Happened: A White House Memoir. 

The White House claims that the book “appears to contain significant amounts of classified information” in a letter addressed to Bolton’s lawyer. 

The letter said that some of the information in the book was classified at the “top secret” level, meaning it “reasonably could be expected to cause exceptionally grave harm to the national security,” and that the book therefore could not be published as is. 

“Under federal law and the nondisclosure agreements your client signed as a condition for gaining access to classified information, the manuscript may not be published or otherwise disclosed without the deletion of this classified information,” it read.

The White House, Bolton, neither the book’s publishers Simon & Schuster have commented on this latest development. 

This letter comes after Trump took to Twitter Wednesday morning to attack Bolton. In a series of tweets, Trump suggested that if Bolton was still the National Security Advisor, that the United States “would be in World War Six by now.”

The book shows that there was a link between the suspension of Ukranian aid and Trump’s request for Ukraine to investigate political rivals. Trump has vehemently denied the two were linked. 

Bolton said earlier this month that he would be willing to testify in the Senate trial if subpoenaed, but Trump said he would attempt to assert executive privilege and block Bolton’s testimony.