President Donald Trump did not appear to understand the significance of a Pearl Harbor memorial during a private tour of the USS Arizona Memorial, according to a new book.

The memorial was constructed in 1962, right above the original USS Arizona, in memory of the more than 2,400 service members and civilians who were killed in the Pearl Harbor attack — some of whom were entombed in the battleship.

According to the Washington Post reporters Philip Rucker and Carol Leonnig, Trump asked his then-chief of staff, John Kelly, "Hey, John, what's this all about? What's this a tour of?"

"He was at times dangerously uninformed," a former senior White House official said, according to the Washington Post.

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President Donald Trump did not appear to understand the significance of the iconic Pearl Harbor memorial in Honolulu, Hawaii, during a private tour of the USS Arizona Memorial, according to a new book by two Pulitzer Prize-winning reporters from the Washington Post.

The book, "A Very Stable Genius," is an account from hundreds of hours of interviews with over 200 sources, according to the Post. Some of its details, which paint an unflattering picture of the president's knowledge of foreign affairs, were corroborated by "calendars, diary entries, internal memos and even private video recordings," The Post reported.

According to the Washington Post reporters Philip Rucker and Carol Leonnig, Trump asked his then-chief of staff, John Kelly, "Hey, John, what's this all about? What's this a tour of?"

"He was at times dangerously uninformed," a former senior White House official said, according to The Post.

Trump appeared not to grasp that this was a hallowed tribute to the more than 2,400 US service members and civilians who died in the 1941 assault, a devastating surprise attack that launched America into World War II. In November 2017, Trump visited the site for the first time and claimed he "read about, spoken about, heard about, studied [sic]."

"And that is going to be very exciting for me," Trump added at the time.

The battleship USS Arizona was attacked by Japanese forces on December 7, 1941, killing 1,177 US Navy sailors and Marines. Over half of the casualties could not be recovered from the underwater site, where the ship still remains.

The memorial was constructed in 1962, right above the original USS Arizona, in memory of the combined 2,341 service members and 49 civilians who were killed in the Pearl Harbor attack.

President Donald Trump, center right, and first lady Melania Trump, center left, throw flower petals while visiting the Pearl Harbor Memorial in Honolulu, Hawaii Friday, November 3, 2017. They were accompanied by US Pacific Command head Adm. Harry Harris, left, and his wife Bruni Bradley. Andrew Harnik/AP

Kelly is a retired four Marine Corps general and a Gold Star father. After he retired from the Marine Corps, he helmed the Department of Homeland Security before being tapped as Trump's chief of staff. Kelly eventually resigned in December 2018 and was replaced with Office of Management and Budget Director Mick Mulvaney, who is currently serving in an acting role.

Authors Rucker and Leonnig write that although Trump "heard the phrase 'Pearl Harbor' and appeared to understand that he was visiting the scene of a historic battle ... he did not seem to know much else," The Post reported.

Trump appears to be aware of some of the history, tweeting in 2016: "Does President Obama ever discuss the sneak attack on Pearl Harbor while he's in Japan? Thousands of American lives lost."

But subsequent tweets made by Trump and First Lady Melania in December 2017 appeared to undercut some of their knowledge. Trump, quoting President Franklin D. Roosevelt in 1941, misquoted his predecessor's famous line, "a date which will live in infamy," and tweeted out "National Pearl Harbor Remembrance Day - 'A day that will live in infamy!'"

In a now-removed tweet from 2017, the first lady said that the Pearl Harbor attack occurred in November, one month before the actual date.

"A Very Stable Genius" will be available on January 21, 2020.