Heather Williams
Former Chatham House Expert

Treaties risk falling victim to the law of diminishing returns. The Partial Test Ban Treaty (PTBT), finalized fifty years ago on 25 July 1963 is a case in point. A creature of its time, the PTBT was designed to stop a Cold War arms race, ease US-Soviet tensions, and limit the environmental damage caused by the superpowers’ regular atmospheric tests. Despite its age, and although its provisions have largely been overtaken by the Comprehensive Test Ban Treaty (CTBT) it is still relevant in today's very different circumstances.  

The PTBT can stand as a model of what William Walker defined as nuclear responsibility: both a 'duty of care' over existing nuclear weapons stocks, and genuine and safe progress towards nuclear disarmament. And as long as nuclear weapons exist, which they will do for the foreseeable future, states must demonstrate nuclear responsibility. The PTBT's success can therefore be an example for today's policy-makers struggling to put CTBT entry into force. Furthermore, it offers hope that patience and confidence-building will lead to further US-Russia arms reductions.

The PTBT had a lengthy gestation. US President Eisenhower suggested limiting nuclear testing, but the US and Soviet Union failed to reach agreement on the limits of contemporary verification techniques and amid worsening bilateral relations. Between the first nuclear test in 1945 and the PTBT in 1963 the US conducted 216 above-ground nuclear tests, compared to the Soviets' 214; the Soviets tested the largest devices, including a 50 mega-ton explosion in 1961, the Tsar Bomba. Soviet Premier Nikita Khrushchev expressed willingness for a treaty that banned all above-ground testing in July 1963. After ten days of negotiations the PTBT was finalized. All states with nuclear weapons have since joined, except for China, France, and North Korea.

Three key factors facilitated this shift in attitude. First, the Cuban Missile Crisis demonstrated to both sides the need to limit the arms race and prevent miscommunication (which also resulted in the establishment of a Washington-Moscow hotline in 1962). Second, the treaty’s concept was narrowed down from its original aim of banning all nuclear testing (which was unverifiable at the time) and abandoned the inclusion of disarmament, which was politically divisive. Finally, and perhaps most importantly, civil society groups (mainly in the West) pressured governments to cease above ground testing due to the detrimental environmental impact. This combination of favourable political circumstances, diplomatic flexibility, and wider civic engagement continue to be essential to successful arms control. 

Political initiatives

The example of the PTBT also illustrates how limited arms control treaties can be used to make progress on the wider agenda. A year before the PTBT negotiations, US President Kennedy gave his Berlin speech calling for the freedom of all Europe in the midst of the Cold War; fifty years later President Obama delivered his own Berlin speech pressing for the final entry into force of the CTBT, in part as a way of reiterating the goal of the 'peace and security of a world without nuclear weapons.'

Furthermore, the process of negotiation and implementation - before full entry into force - can bring tangible and intangible benefits. In the case of the PTBT, the decade of discussion before its final agreement helped lay crucial groundwork not only for the treaty, but also for further successive arms control agreements, in particular SALT I and eventually the CTBT. And the final substance and structure of the PTBT allowed the United States and Soviet Union to begin to build mutual trust. In particular, the PTBT's dispute resolution mechanism prevented tensions over what otherwise could have been perceived as violations, but which were accidental leakages from underground testing.  

Although the CTBT has still not entered into force (despite being finalized in 1997), it can already list some achievements: notably, the establishment of a highly effective International Monitoring System and the spread of an increasingly strong norm against testing. Final entry into force will depend on its ratification by the last eight of the 44 'Annex 2' countries (China, Egypt, India, Iran, Israel, North Korea, Pakistan and the United States). It is hoped that the example of the PTBT and the model it provides for nuclear responsibility will help incentivize at least some of these states to move the process forward.