Ex-defense secretary Jim Mattis has book coming this summer

Former Secretary of Defense Jim Mattis has a book coming out this summer, but he warns that it will not be a "tell-all" about President Donald Trump

"My purpose in writing this book is to convey some of the lessons I learned in 43 years of service for those who might benefit, whether in the military or in civilian life," Mattis, 68, said in a statement. "I'm old-fashioned: I don't write about sitting Presidents, so those looking for a tell-all will be disappointed. I want to pass on the lessons and experiences that prepared me for challenges I could not anticipate, not take up the hot political rhetoric of our day."

The book's title comes from Mattis' call sign, "Chaos," while he led the 7th Marine Regiment in the mid-1990s. (Trump had favored calling him "Mad Dog," a nickname Mattis disdained).

Trump responded by disparaging Mattis' leadership at the Pentagon and by stating, falsely, that he had "effectively" fired his defense secretary. Mattis has since been virtually silent about his time in the administration.