Bill O'Reilly's next subject in his million-selling "Killing" series isn't just one person but a whole country: Japan.

"Killing the Rising Sun," which focuses on the final year of World War II in the Pacific, is coming out Sept. 13.

O'Reilly told The Associated Press during a recent interview that he and his co-author, Martin Dugard, have researched the conflict from the American and Japanese sides and will take a close look at the debate over whether President Harry Truman should have ordered the atomic bomb attacks on Hiroshima and Nagasaki.

"When you hear about some of the people who were opposed to dropping the bomb, the names will surprise you," O'Reilly says.

The Fox News host also says the book will include letters from former Presidents Jimmy Carter, George H.W. Bush and George W. Bush on whether they would have dropped the bomb.

Wednesday's announcement about the book came two days after John Kerry became the first sitting U.S. secretary of state to visit the Hiroshima memorial, described by Kerry as a "gut-wrenching display."

"Killing the Rising Sun" is the sixth of nine planned books in a series that has made O'Reilly and Dugard the most widely read historians in the country despite frequent criticisms about their accuracy. The books, which include "Killing Jesus" and "Killing Lincoln," routinely sell more than 1 million copies in hardcover, a rare achievement for nonfiction releases.

Publisher Henry Holt and Co. told the AP on Wednesday that more than 14 million copies of O'Reilly's series are in print worldwide.

O'Reilly acknowledged that "Killing the Rising Sun" is a "provocative" title, but he said an even more direct one was planned.

"We were originally going to call it 'Killing Japan,'" he said, adding that he was "happy" with changing it to "Killing the Rising Sun."

"At this stage," he said, "I'm not worried whether people like it or not."

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