I have enormous respect for Mr. Ellsberg, and I'd highly recommend this article and anything else he's written. His book 'Secrets' that he wrote a few years back is excellent.
But the scientists knew something else that was unknown to the public and even to most high-level decision-makers. They knew that the atomic bombs, the uranium and plutonium fission bombs they were preparing, were only the precursors to far more powerful explosives, almost surely including a thermonuclear fusion bomb, later called the hydrogen bomb, or H-bomb. That weapon—of which we eventually came to have tens of thousands—could have an explosive yield much greater than the fission bombs needed to trigger it. A thousand times greater.
Moreover, most of the scientists who focused on the long-run implications of nuclear weapons, belatedly, after the surrender of Germany in May 1945 believed that using the Bomb against Japan would make international control of the weapon very unlikely. In turn that would make inevitable a desperate arms race, which would soon expose the United States to adversaries’ uncontrolled possession of thermonuclear weapons, so that, as the scientists said in a pre-attack petition to the president, “the cities of the United States as well as the cities of other nations will be in continuous danger of sudden annihilation.” (In this they were proved correct.) They cautioned the president—on both moral grounds and considerations of long-run survival of civilization—against beginning this process by using the Bomb against Japan even if its use might shorten the war.
Of course, our government had put a general in charge of the Manhattan Project, instead of the scientists. When the scientists wrote this petition, they submitted it properly, through channels. Which meant it went to Gen. Groves. Gen. Groves decided not to pass it along to the Secretary of Defense or the President. They never saw it. After the war, the petition was then classified 'secret' to make sure the American people never knew the views of the scientists who were most familiar with the bomb.
America Has Been Asleep at the Wheel for 64 Years. But its not like we just dozed off. More like we've been drugged into submission by generals who decided we didn't need to know enough to question their sacred judgments.
Its enough to make one appreciate why the founding fathers of this country viewed 'standing armies' as the greatest threat to the freedom they had just fought for and won.