December 07, 1959
C. L. Marshall, Director, Division of Classification, to A. A. Wells, Director, Division of International Affairs, 'Cooperation in the Field of Gas Centrifuge'
US Atomic Energy Commission classification director C. L. Marshall explains to international affairs director A. A. Wells that the design for the gas centrifuge must be classified for fear of providing an “unfriendly nation” a low-energy consuming method for “the separation of heavy isotopes…an important part of a [nuclear] weapons program.”