When the United States established diplomatic ties with the Soviet Union in 1933, it did more than normalize relations with the new Bolshevik state--it opened the door to a parade of Russian spies. In the 1930s and 1940s, Soviet engineers and technicians, under the guise of international cooperation, reaped a rich harvest of intelligence from our industrial plants. Factory layouts, aircraft blueprints, fuel formulas--all were grist for the Soviet...