U.S. President Donald Trump reportedly said that as many as 100 million people could have been killed had the United States gone to war with North Korea.

Doug Wead, a conservative author and former adviser to two American presidents, revealed the remarks in a new book called "Inside Trump's White House: The Real Story of His Presidency."

In the book published Tuesday, the author quoted Trump as saying that 30 to 100 million people could have been killed if the U.S. had gone to war with North Korea.

Trump reportedly said, without evidence, that if former U.S. President Barack Obama had stayed in the White House longer, the U.S. would have gone to war with North Korea. 

Wead also wrote that Trump expressed dissatisfaction with "rich" allies, saying that the people who treat the U.S. the worst are its allies.

In particular, Trump reportedly mentioned the deployment of the U.S. THAAD anti-missile system to South Korea and said that the U.S. "gives so much and gets nothing."

[Photo : YONHAP News]