HARRY TRUMAN strolled casually around the table in the Cecilienhof Palace at the conclusion of the July 24, 1945 session of the Potsdam Conference -- indeed so casually, or so it seemed, that he did not even bother to take his interpreter with him.

The United States, Truman told Joseph Stalin, "had a new weapon of unusual destructive force."

ythe Soviet dictator was no less casual in his reply -- he was glad to hear about it and he hoped that the United States would make "good use of it against the Japanese."

In fact, there was nothing casual about the exchange. Truman's saunter was the result of serious deliberation, and Stalin almost surely knew exactly of what Truman spoke -- the atomic bomb.

Nuclear weapons were used twice within a fortnight, bringing World War II to a swift end. The atomic age was born. Thereafter, nuclear weaponry became a central issue between the United States and the Soviet Union. In The Winning Weapon, Yale professor Gregg Herken, making use of the considerable documentation that has become available in recent years, offers a carefully-researched, lucid and searching history of the connection of the atomic bomb to American diplomacy and relations with the Soviet Union after World War II. It is a work that illuminates some of the most basic dilemmas and challenges that the United States faces today. Fortunately, enough time has passed that the whole revisionist-orthodox debate on the Cold War can be put aside in favor of such complex and intensely researched work.

Much of Herken's story concerns the American effort to figure how the atomic bomb related to everything else. While the United States may have had a nuclear weapons monopoly after the war, there was great confusion about its significance. As Herken writes, "There was no compelling direction for U.S. atomic-energy policy following the surrender of Japan."

It was generally, if vaguely, thought that the bomb would provide some kind of upper hand in dealings with Stalin. This it did not do. It may have made Stalin more cautious. That it did not do more could have been the result of the fact that the nuclear arsenal was tiny. ("You could have put the entire nuclear weapons program under your pillow" one of the first commissioners of the Atomic Energy Commission noted not long ago.) Also, the bomb was too "absolute" to be brought into the system of diplomacy -- for instance, it could not easily be brought to bear to change the composition of the Rumanian cabinet. In addition, Herken observes that the United States held out not only a vague threat to the Soviet Union, but also a considerable, even generous promise -- a promise of cooperative control of the atomic bomb.

The Soviets spurned the approaches, and efforts to work out a cooperative solution failed quickly enough. But perhaps the real options were few. How could a cooperative system for something so critical as atomic energy have ever been created between the United States and the Soviet Union, at least at that time? On what basis? As Secretary of War Henry Stimson noted at one point: "No world organization containing as one of its dominant members a nation whose people are not possessed of free speech . . . can give effective control of this agency with its devastating possibilities." Free speech was really a symbol of the vast gulf between two systems so fundamentally different. Could the United States and a totalitarian, closed Stalinist Russia, have found mutually acceptable and stable procedures for common management that could survive and would not been seen as quite dangerous by one side or the other -- or both? How could these diverse political systems mesh? What shared assumptions existed? In somewhat different form, these remain critical questions that perplex today.

A kind of Pax Atomica did finally result, but one based neither on comparitive management nor on American monopoly, but rather on each side's having its own arsenal. Thus, it has been rooted in the premise of deterrence through counter-strike, whether explicit or implicit. The idea was set out in 1946 by Arnold Wolfers, a leading thinker on international relations, when he observed that "retaliation must occupy a decisive place in any over-all policy of protection against the atomic danger." He went on to say that "deterring power" might well provide "the best guarantee of peace and tend more than anything else to approximate the views and interests of the two countries."

Thus, it is not surprising, even if ultimately not terribly comforting, that competition over atomic wars developed between the United States and the Soviet Union -- a competition that has paradoxically meant both greater stability and permanent danger. What did surprise was timing. The Soviet bomb came a good deal earlier than many in the United States had expected. Here Herken offers a very interesting account of the development of strategic thinking and of the varying ways that American policymakers conceptualized the "atomic secret." Was it specific scientific knowledge? Was it access to the raw materials? The "secret" was a source of both great uncertainty and of considerable misunderstanding. As to there being an actual secret, Henry Stimson was pretty much on target when he said, "We do not have a secret to give away -- the secret will give itself away." The critical secret may have been the knowledge given away in July and August, 1945 -- that a bomb was not only theoretically possible, but that it worked.

The Americans did believe that they had established a preclusive raw materials monopoly. In retrospect, this was certainly a most reasonable and sensible policy objective. Unfortunately, it appears they had overlooked or were unaware, at least for considerable time, of a very significant Soviet uranium mining operation in East Germany, as well as of uranium resources in the Soviet Union. Or were they unaware? On this key question, Herken is somewhat confusing. Perhaps the information that was available to Washington was not well-integrated into the over-all policy consideration.

Also Herken's treatment of the question of espionage and traitors is less than clear, although one suspects that the documentation available to historians on this subject is quite incomplete. Herken tends to play down its significance on the basis that there was not a real secret to steal. Still, the Soviets had quite a potentially useful stream of information coming from such spies as Donald Maclean, who was in a key liaison position on atomic matters between the United States and Britain. How much good did the spies do? How much time was saved for the Russians, if the main task seems to have been organizational? Still, at the very least, the Soviets would have had a pretty good idea of the nature and tempo of the American program. These questions remain very much open.

In discussing the political ramifications of the spy cases, Herken gives in to the tendency to assume that political leaders have a fair amount of latitude to control events. He does not convincingly show that the publicizing of the first postwar spy scandal (in Canada) was actually much dictated by the domestic U.S. debate over control of atomic energy. Nor was Truman, beset by many pressures on many issues, in much of a position to nip in the bud fear about spies.

As it was, most American officials were shocked by the Russian atomic test in 1949. No doubt, there was a strong element of wish in the conviction that the Soviet bomb was still a few years off, for the world without a Soviet bomb was certainly a safer, more comfortable world. Also, "expertise" could become a device to screen out unwelcome information. Herken quotes scientist Leo Szilard -- to whom Secretary of State James Byrnes had passed the assurance that there was no uranium in Russia: "If you are an expert, you believe that you are in possession of the truth, and since you know so much, you are unwilling to make allowances for unforseen developments." It is a good maxim to keep in mind whenever absolute certainty is offered, whatever the topic.

As it was, the Soviet bomb did introduce a more dangerous world. "The Russian atomic test," writes Herken, "signalled not only the end of American nuclear hegemony but the start of the Soviet-American arms race." The first proposition is certainly true. But, given the fundamental gap between the United States and the Stalinist state, it might be more correct to say that the inevitable race really began four years earlier, at that moment in Potsdam when Truman sauntered in so seemingly casual a manner around the table to exchange a word with the soviet dictator.