The great game began even before the Grand Alliance formally split along ideological lines. The KGB had several sources inside Los Alamos, where scientists worked in secrecy to develop America's first atomic bomb. Unknown to one another, scientists Klaus Fuchs and Ted Hall both passed on details of how to detonate nuclear weapons by "implosion" -- a principle so new to Soviet science that there was no equivalent word in Russian.

In 1949, the Soviets exploded their first atom bomb. Triggered by implosion, it copied key elements of the American bomb that destroyed Nagasaki. The atom spies had saved the Soviet Union perhaps two years of research.
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