Einstein and other scientists were worried that Hitler had embarked on an atomic bomb project, which is why Einstein's comment continued, ''... but there was some justification - the danger that the Germans would make them.'' (My source for this quote, and inspiration for this column, is Martin J. Sherwin's milestone book, ''A World Destroyed.'')

Motivated by an urgent impulse to achieve the atomic weapon before Hitler, a collection of the world's most brilliant physicists went to work. The first self-sustaining chain reaction was created at the University of Chicago in December 1942, but then, unknown to the scientists, a strange thing happened. Winning the race against the Nazis stopped being the paramount concern. As the policy chiefs of the Manhattan Project began to see exclusive possession of the bomb as a source of tremendous diplomatic power, they recognized its potential as an unprecedented political check on the Soviet Union after the war. The bomb had a new, if as yet unadmitted, purpose.

In November 1944, the United States discovered that Germany's atomic program was embryonic: There was no real threat of a Nazi bomb. Sherwin suggests that this crucial intelligence may have been kept from the Los Alamos scientists ''in order not to dampen their enthusiasm.'' By this point in the war, there was no longer any real danger of an Allied defeat, yet the Manhattan Project proceeded with more urgency than ever. The policy chiefs had an eye as much on a post-war rivalry with the Soviet Union as on the endgame with Germany and Japan, which gave them a whole new motive for using the bomb as soon as possible.

Today marks the anniversary of the American atomic bomb falling on Hiroshima. The unfinished debate about whether that attack, and the subsequent bombing of Nagasaki, were justified has always focused narrowly on the question of the war with Japan. Didn't the atomic bomb, in effect, spare the lives of all the leathernecks and GI's who would otherwise have landed on the beaches of the die-hard island nation? What else could Truman have done? These questions have stymied the American conscience, making it impossible to seriously reckon with that crossing of the nuclear threshold, which in turn inhibits our moral reckoning with our present nuclear arsenal.

But what if the invasion of an all-but-defanged Japan was, and remains, a red herring? What if, just as the Nazi threat fell by the wayside, the Japanese threat was not the real issue by then either? What if, by the summer of 1945, the overriding purpose of the atomic bomb was not to end a conflict against Japan, but to control the shape of an anticipated conflict with the Soviet Union? What if it was not Emperor Hirohito we were mainly trying to terrorize, but Premier Stalin? Not a last shot against the Axis powers, but a first shot against the Kremlin?

In war and politics, there are never one-factor answers to complex questions. In truth, the atomic bomb was a last shot and a first shot both. The point of my asking is simply to suggest that, as a people insisting on a narrative in which Hiroshima marked the end of a conflict instead of the beginning of one, we have given ourselves a pass on a far more troubling question.

If we used the nuclear weapon as much to send a signal to the Soviet Union as to end World War II, then all the wickedness unfolding from that use - not only the arms race, but the demonic new idea that national power can properly depend on the threat of mass destruction - belongs to us. If Saddam Hussein wants weapons of mass destruction for the sake of the strategic diplomatic power they will give him, he is playing by rules written in Washington. There are two ways to use the nuke - as a source of world destruction, and as a source of world power. We did the former at the end of World War II, which was the exact beginning of the Cold War. We have been doing the latter every day since. And why should Hussein not want to imitate us?

The bombing of Hiroshima was a great crime. That the United States of America has yet to confront it as such not only leaves the past with unfinished business, but undercuts the possibility of present moral clarity about the exercise of American power and leaves the earth's future tied to a fuse that we set burning 57 years ago today.

James Carroll's column appears regularly in the Globe.

© Copyright 2002 Globe Newspaper Company

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