Bull used this opportunity to lay out his thinking on the role that disarmament could play in securing peace more adequately than it had in the past. He was Clausewitzian in his approach, arguing that wars were caused by political tensions rather than the mere accumulation of arms. Hence peace had to be sought more through political agreement and understanding than disarmament. He was opposed to the development of any one central world authority, as some (including Noel-Baker) were arguing that the United Nations should become. Bull feared that such a body would be too powerful and oppressive. He preferred a diversity of centres of power which might lead to friction and wars from time to time, but one which also enabled freedom and individuality to survive in the international community.

He also dismissed the notion that states would substantially disarm by mutual agreement, as most governments and their electorates believed that they needed weapons for the defence of their liberty or to hit back at others who seriously infringed their freedom of action. Where disarmament had some real prospects, Bull argued, was in the field of limited scope agreements, presciently pointing the way to the limited, strictly defined arms control agreements of the 1960s, 1970s and 1980s such as SALT I and II, the Partial Test Ban Treaty, the ABM Treaty and the Nuclear Non-Proliferation Treaty itself. This latter treaty, through attempting of necessity to be universal in its membership, did not fulfil Bull’s criteria for success as fully as the others. Unsurprisingly it has remained weaker in its effect and has been defied by notable proliferating powers. It has also been frustrated, as many have argued including Bull, by the tardiness of the five declared and accepted nuclear weapon states to reduce their own nuclear arsenals.

Bull made a distinction between nuclear weapons intended for deterrence and those intended for use in combat. He accepted the need for weapons to serve the first purpose, invalidating Noel-Baker’s claim that ‘if war is an anachronism then armaments are too’. It was the very frightfulness of nuclear weapons that made war anachronistic. They had a continuing and positive role to play—to make war less frightful would be to make it more probable Bull argued. Bull however refused to accept that nuclear weapons should be developed as a means of combat. Their effect would be too horrible, and the use of low yield nuclear weapons in the early stages of a conflict was likely to encourage others to escalate their usage of them, resulting in a holocaust. To that extent, Bull shared Noel-Baker’s view of nuclear weapons. He recognised them as a formidable problem for statesmen and diplomats to deal with, and for defence ministries and armed services to keep tightly under control, but in the context of the world order then extant in the 1950s Bull thought that the objectives of the nuclear abolitionists such as the Campaign for Nuclear Disarmament were futile.

Bull came quite early to believe that it would be morally wrong and militarily counter-productive to be the first to use nuclear weapons, particularly in a conflict between the North Atlantic Treaty Organization (NATO) and the Warsaw Pact. He joined those who advocated a ‘No First Use’ agreement between both sides and put himself into a position of lasting difference with United States and NATO policymakers. Western leaders, looking at the unfavourable balance of their conventional forces with those of the Warsaw Pact, believed that a credible threat to use nuclear weapons first in reply to any Soviet use of massive force in Europe or elsewhere was a vital part of deterrence. And the fact that the Soviets continued to advocate such a ‘No First Use’ agreement made it seem only less desirable from a NATO perspective. Bull did not constantly harp on the matter, but he regularly drew fire from NATO-member officials such as Sir Michael Quinlan when he expressed his viewpoint in international conferences.

The logic of his stance on nuclear weapons as disincentives to war led Bull to oppose the idea of strategic defence against an enemy’s nuclear weapons. He was explicit on this point in his review article of 1959 and he kept to these views, especially during the heated debates of the 1970s and 1980s on programs such as US President Ronald Reagan’s Strategic Defence Initiative (SDI).