In a letter to former national security adviser John Bolton's attorney, the White House said Bolton's upcoming book contains classified information that must be removed before it can be published.

In the letter to the lawyer, Charles Cooper, dated Jan. 23, a National Security Council aide wrote: "Based on our preliminary review, the manuscript appears to contain significant amounts of classified information. It also appears that some of this classified information is at the top-secret level."

"The manuscript may not be published or otherwise disclosed without the deletion of this classified information," added Ellen Knight, NSC senior director for records, access and information security management.