Former first lady Michelle Obama reportedly rips President Trump's spreading of the "birther" conspiracy theory against her husband in her upcoming book.

In excerpts from her memoir "Becoming" obtained by The Washington Post, Obama says she will "never forgive" Trump for the "xenophobic" claims that her husband, former President Obama, was not actually born in America.

"The whole thing was crazy and mean-spirited, of course, its underlying bigotry and xenophobia hardly concealed," the former first lady writes. "But it was also dangerous, deliberately meant to stir up the wingnuts and kooks."

"What if someone with an unstable mind loaded a gun and drove to Washington? What if that person went looking for our girls? Donald Trump, with his loud and reckless innuendos, was putting my family's safety at risk. And for this I'd never forgive him," she continues.

Trump responded Friday morning in comments to reporters as he left the White House for a trip to France to mark the 100th anniversary of the end of World War I.

"I guess she wrote a book. She got paid a lot of money to write a book," the president said. "And they always insist that you come up with controversial - well, I'll give you a little controversy back. I'll never forgive him for what he did to our United States military. By not funding it properly, it was depleted."

Trump added, "I'll never forgive him for what he did in many other ways, which I'll talk to you about in the future."

The book, which is set to release Tuesday, details the first lady's early life in Chicago all the way through to her time as first lady, and includes her feelings of shock and disbelief following Trump's election in 2016.

The comments are some of Obama's most direct aimed at the current president, whom she has mostly avoided criticizing since leaving the White House last year.

Other criticism in the book was aimed at Trump's comments about women on the now-infamous "Access Hollywood" tape, as well as his conduct during debates with his 2016 Democratic opponent, Hillary Clinton.

Obama plans to launch a 10-city book tour that is scheduled to kick off Tuesday in her hometown of Chicago.

-Updated at 2:52 p.m.