From a Pentagon strategic research officer, Daniel Ellsberg has frightened the United States, and was seen by American authorities as "America's most dangerous man" when he published top-secret documents which expose the US government's lies about the Vietnam War. After reading all the 7,000 pages of top secret documents (later known as "Pentagon Papers"), Ellsberg realized that the Vietnam War was essentially a war by the United States and it has been maintained through four successive presidencies, although they all know it is an "unwinnable" war and the reason is that they do not want to "lose face". With a lot of good material, realistic and lively, the book is consistently ranked among the best sellers in the US and reprinted many times.