roads.
After the early disasters, the Soviet advance seemed almost miraculous: the Leningrad blockade broken in January 1944, the breakthrough to Romania in February and March, Odessa liberated in April, the Crimea completely cleared in May, Finland finished in June, the western Ukraine liberated in July all the way to Warsaw, Romania surrendered in August, Estonia and Latvia cleared in September, Hungary, eastern Czechoslovakia and northern Norway entered in October. American Lend-Lease was feeding several million Soviet civilians and half the Red Army. Stalin would acknowledge that about two-thirds of his major industries were being rebuilt with US equipment or technical assistance. But the blood that was spilled on the way west to Berlin was Russian blood. In 1943, Franklin Roosevelt's adviser and aide Harry Hopkins had noted that the Soviet Union “is the decisive factor in the war… [and] without question… will dominate Europe on the defeat of the Nazis… ” Certainly Stalin meant to do so. He also understood, he told Milovan Djilas one evening in March 1944, that the West would resist him:
Stalin then invited us to supper, but in the hallway we stopped before a map of the world on which the Soviet Union was colored in red, which made it conspicuous and bigger than it would otherwise seem. Stalin waved his hand over the Soviet Union and, referring to the British and the Americans, he exclaimed, “They will never accept the idea that so great a space should be red, never, never!”
The prospect of an eventual end to the terrible war stirred old enmities. Averell Harriman, for one — since October 1943 the US ambassador in Moscow — took the Soviet determination to collect its spoils and secure its dominance as a threat. “What frightens me [about Soviet policy toward Poland and Eastern Europe],” he wrote Secretary of State Cordell Hull on September 20, 1944, “is that when a country begins to extend its influence by strong-arm methods beyond its borders under the guise of security it is difficult to see how a line can be drawn. If the policy is accepted that the Soviet Union has a right to penetrate her immediate neighbors…. penetration of the next immediate neighbors becomes at a certain time equally logical.” Harriman's analysis was an early version of the domino theory that would shape American thinking about the Soviet Union for most of the rest of the twentieth century. It was hardly logical from a military point of view, since control and supply both attenuate with distance. Nor could it take into account what Harriman was not yet aware of, the coming US monopoly on the atomic bomb. But Harriman had seen ravaged Europe and knew Britain was nearly bankrupt; he had smelled the excitement in Moscow at the prospect of territorial gains and bounteous reparations; and he understood that the supply lines would be even longer from the United States.
Winston Churchill was more pragmatic or more cynical. Meeting with Stalin in Moscow in October 1944, he proposed that the two leaders “settle about our affairs in the Balkans… Don't let us get at cross purposes in small ways. So far as Britain and Russia are concerned, how would it do for you to have ninety per cent dominance in Romania, for us to have ninety per cent of the say in Greece, and go fifty-fifty about Yugoslavia?” Churchill wrote out the percentages, adding “Hungary… 50–50 %” and offering Stalin 75 percent dominance in Bulgaria, and pushed the paper across the table. “There was a slight pause. Then [Stalin] took his blue pencil and made a large tick upon it, and passed it back to us. It was all settled in no more time than it takes to set down.” It was hardly settled at all, if only because Stalin expected to dominate the nations on Churchill's list, with the possible exception of Greece, not fifty or seventy-five or ninety but a full one hundred percent.
In February 1945, Soviet agents in North America delivered a rich harvest of atomic espionage to Moscow Center. Alan Nunn May weighed in first. Colonel Nicolai Zabotin, the GRU officer in Ottawa, had assigned a young lieutenant on his staff to control Nunn May after orders came from Moscow sometime late in 1944 to reactivate the British scientist, who had not been approached since he left England. The young officer, whose name was Ange-lov, had simply gone to Nunn May's apartment on Swail Avenue in Montreal, knocked on the door and identified himself. Renewed contact disturbed Nunn May, who seems to have imagined he could withdraw his services unilaterally; he told Angelov that his old connection had been severed and that he was under observation by Canadian security. Angelov thought Nunn May “a man who seemed to be trapped,” but he was not impressed; he had a job to do. “I told him quite bluntly that I didn't believe him and that Moscow had an assignment for him,” the officer bragged afterward to Igor Gouzenko. “If he refused the assignment it would be his worry, not mine. He seemed to shrink up before my eyes. Finally, he asked me what I wanted. I told him Moscow wanted a report on atomic bomb research in Canada and the United States.” Nunn May asked for a week lo prepare the report. They met a second time a week later at Nunn May's house.
Igor Gouzenko saw the document that Nunn May prepared when Zabotin passed it to him for ciphering. He described it in 1948:
The report obtained from Dr. May was extensive and comprehensive. It came in two sections…
One part, covering the technical processes being followed in the bomb's construction, was ten single-spaced typed [pages]…
[The second part] was a general description of the atomic project's organization in Canada and the United States. It explained the structure of the whole Manhattan Project and the War Department officials and scientists in charge…
Zabotin was particularly delighted over Dr. May's naming of the highly hush-hush plants and the nature of the work being done at Oak Ridge, Tennessee, at the University of Chicago, at Los Alamos, New Mexico, and at Hanford, Washington.
Gouzenko advised Zabotin that the technical part of the document, with its new and unfamiliar terminology, would be difficult to cipher and decipher without “costly errors.” Zabotin decided to send it by diplomatic pouch. Gouzenko proceeded to cipher the general description, which was transmitted to Moscow by cable. The GRU shared it with the NKGB — the NKVD foreign intelligence division — and Vsevolod Nikolayevich Merkulov, the NKGB head, incorporated it into a summary of the Anglo-American program that went to NKVD commissar Lavrenti Beria on February 28, 1945- Besides the details of organization and personnel that delighted Zabotin, Merkulov's summary mentioned “two methods under development for activating the bomb: (1) the ballistic method and (2) the method of implosion” — another reference, independent of David Greenglass, to the radical new technology Los Alamos was inventing for assembling a critical mass with high explosives. The NKGB summary also included a discussion of sources of uranium ores and of American efforts to gain “unlimited control over mining of uranium ores in the Belgian Congo.” The likeliest source of this information was Donald Maclean.
Igor Kurchatov reviewed espionage material on March 16, 1945, that appears to have included the first part of Nunn May's report. “The material is of great interest,” Kurchatov wrote with excitement: “Along with methods and schemes which we have developed independently it discusses possibilities which we have not yet considered.” One possibility concerned making a bomb with a nuclear core diluted with hydrogen — with uranium or pluto-nium hydride, that is. Because the hydrogen would slow secondary neutrons, increasing the number of fissions and therefore reducing the amount of uranium or plutonium needed (by a factor of twenty, the espionage document estimated), Edward Teller had championed such a scheme at Los Alamos. Further examination had made clear to the Americans what Kurchatov immediately deduced, that a hydride core, with its slower reaction rates, would blow itself apart before the reaction could chain through enough generations for an efficient explosion. Work on a hydride gun essentially ended at Los Alamos in August 1944, but someone like Nunn May, collecting information far from the source, might not have known that. Kurchatov was eager to know if this odd bomb design had been studied only through calculations or experimentally — if experimentally, then “that would mean that the atomic bomb has already been realized [by the Anglo-Americans] and that U235 has already been extracted in large quantities.” He suggested “obtaining several grams of highly-enriched uranium from the American laboratories mentioned in the espionage material” he was reviewing. By “obtaining,” of course, he meant stealing.
The more significant possibility discussed in the materials Kurchatov reviewed on March 16,1945, concerned implosion. Kurchatov gave no indication that he had heard of implosion before reviewing the documents in hand even though implosion is mentioned briefly in Merkulov's February 28 summary. The Soviet physicist was impressed:
The “implosion” method uses tremendous pressures and velocities created by explosion. It is said in the
