Oppenheimer led the successful effort on the atomic bomb in the Manhattan Project during World War II. He soon realized that security from atomic bombs would come only from some form of transnational organization, and began advocating the use of nuclear energy for peaceful purposes. Earlier, Oppenheimer was a professor of physics at the University of California, Berkeley, and at the California Institute of Technology. He was an extraordinary teacher and created a thriving group of theoretical physicists in the US. From 1947 to 1966, he served as the Director of Princeton's Institute for Advanced Study. 

In 1964, the International Atomic Energy Agency appointed Oppenheimer to sit as an expert in the first meeting of the Scientific Council of the International Centre for Theoretical Physics. He was chairman of the first ICTP Scientific Council, held in Vienna in May 1964, and a member at the two following sessions. Being unable to attend the third meeting, he sent a letter to the Chairman, in which he appreciated the role that the young institution had played, in only one year of its existence, as a forum for international cooperation and consequently as an institution of excellence in theoretical physics.

“In all the work at the Centre of which I know, very high standards prevail. In less than a year it has become one of the leading institutions in an important, difficult and fundamental field.”