The first informal contacts between Soviet and CERN scientists probably took place at the Atoms for Peace conference in Geneva in September 1955. Exchange visits between scientists from CERN and the Joint Institute for Nuclear Research (JINR) were suggested in 1957, but there was little progress until N. Bogolubov of JINR raised the subject again on 4 February 1959. CERN’s director-general C. Bakker replied on 5 March that he was, in principle, strongly in favour of the idea, and he began to look into the practicalities. (See their letters here.)
Bakker chaired an informal gathering on International Cooperation in the Field of High Energy Physics Accelerators in September 1959. After more consultation with CERN’s member states he was able to report to Council on 1 December 1959 that "all the delegations were in favour of such exchanges provided they were reciprocal", and the Draft Proposal was approved the following day.