Aiken drafted in additional personnel to the Irish Mission to the UN in the run-in to the XVIth UN Session. Seán Ronan, the head of the political and information divisions at headquarters in Dublin, was sent as a delegate to the First Committee of the UN, involving him intensely in Aiken’s non-dissemination efforts. His insider account reveals some of the dynamics and calculations at play in the building, as Ireland managed a balancing act of engineering consensus between East and West. In large part, the Irish Mission crafted the resolution’s language to skirt the issue of alliance nuclear sharing in a bid to manufacture unanimity. The Irish had pondered co-sponsoring a Swedish draft resolution but anticipated that it would face resistance from NATO comparable to earlier iterations of the Irish resolution. Similarly, Ireland neglected to mention a proposed new disarmament committee in the draft resolution – there was no guarantee that it would form and report expeditiously. Finally, by drawing on the instrument of acclamation, the Irish sidestepped French objections and gained universal approval for Resolution 1665 (1961), wrapping the resolution in universal legitimacy. 

The arrival of the new U.S. president, John F. Kennedy, in office in 1961 encouraged Aiken to redouble his efforts. He searched for signs of change in the Kennedy administration. He was nevertheless guarded,  appreciating that the arms control ambitions of the United States did not necessarily or completely align with Ireland’s disarmament aspirations. He understood that progress required educating public opinion to recognize that general and complete disarmament could, given the vested interests, take generations. A step-by-step, gradualist approach therefore had to be adopted. He reiterated his philosophy of expanding areas of law, adopting a regionalist approach, and assuming a preventive orientation in a commentary on Kennedy’s article in the Bulletin of the Atomic Scientists in November 1960, which was itself based on Kennedy's campaign speech earlier that year.

Aiken’s landmark address to the plenary of the UN General Assembly on 19 September 1958 launched his non-proliferation campaign. It is the first time he publicly identified stopping the spread of nuclear weapons as a concrete step in the collective interest to unblock the disarmament impasse, preventing a runaway arms race among the powers of the Earth. It was clearly framed as part of his wider campaign for global governance based on the rule of law rather than the threat of force. For Aiken, the challenge was stabilizing the arms race and generating trust to construct a world order based on justice and law – “to preserve a Pax Atomica while we build a Pax Mundi.” This speech was a critical departure. The widespread positive reception encouraged Aiken, persuading him to draft a formal resolution.