Without offering specifics about the letter's contents, the New York Times first reported its existence in September 2017, saying the letter was turned over to Mueller's team and was being described as "an unvarnished view of Mr. Trump’s thinking."
The letter had been put together by the president's senior aide Stephen Miller, based on "arguments and specific language" dictated by Trump, Miller's own research, and then "several rounds of edits" from the president, according to Mueller's report.