FOREIGN ýRELATIONS, 1950-, VOLUME I


PM Piles
The Secretary of State to the Chairman of the United States Atomic
                   Energy Commission (Dean)'

SECRET                             [WASHINGTON,] August 22, 1950.
  DFAR MR. CHAIRMAN: International control of atomic/energy is
on the agenda for this fall's session of the United Nations General:
Assembly. In the debates on this agenda item, it is the intention of the
United States Government to continue its support of the United
Nations plan of control.
   In a letter dated April 20, 1950, I asked the Atomic Energy Com-
 mission for a current evaluation of the United Nations plan. In a
 letter dated June 26, 1950 from Sumner T. Pike, Acting Chairman, I
 received assurance that there have been no new scientific discoveries
 known to the Commission which altered the situation.
   The Commission's letter, however, identified two technical develop-
 ments which might have some bearing on control problems and three
 major changes in the technical situation which have occurred since
 the plan was developed and approved.
   It is important to be certain whether it would be technologically
 feasible to establish the type of control envisaged in the United
 Nations plan and, further, whether the plan, once established, would
 be effective.
   One technical development mentioned in the letter indicates that
 it might be possible to produce not only plutonium from uranium and
 tritium from lithium, but also U-233 from thorium, without the
 operation of reactors. The United Nations plan makes no distinction
 between the controls which the international agency would exercise
 over uranium and thorium. Since the plan also provides that the
 international agency would own, operate and manage all facilities
 that make or produce dangerous quantities of nuclear fuel-which,
 by definition, includes both fusionable and fissionable materials-it
 would appear that the United Nations plan would meet the dangers
 inherent in this possible development. I should like the views of the
 Commission on this point.
    The other technical development mentioned in the letter relates to
  the possible development of thermonuclear weapons. As the Commis-i
  sion's letter states, an atomic explosion using plutonium, U-235, or'
  U-233 is necessary to start a thermonuclear reaction. It follows then,
  if fission weapons were effectively eliminated, no thermonuclear
  weapon could be made. As for the point that tritium must be con-

    Commissioner Gordon E. Dean was appointed Chairman of the United States
    Atomic Energy Commission effective July 11, 1950.


82--