Compliance with international disarmament and non-proliferation treaties is key to their success and a crucial element of international security. Depending on the time when the treaties were concluded and the particularities of the respective weapons, states have chosen different ways of dealing with compliance – from the minimal compliance procedures with no verification whatsoever in the 1972 Biological Weapons Convention to the elaborate compliance and verification system of the 1992 Chemical Weapons Convention. For all treaties, cases of suspected or proven non-compliance have been rare. Yet, those few cases of serious and intentional treaty violations that did occur have posed, and are still posing, significant challenges for the treaty regimes and for international security in general. These cases have also exposed one basic problem of disarmament and non-proliferation agreements: the difficulty of enforcement. The existing treaties are usually based on the assumption of a shared interest of all states parties to ensure and maintain compliance in case of violations. And in the absence of an overarching enforcement authority in the current international order, the power to enforce international rules rests with the UNSC. The availability, strength and effectiveness of enforcement measures in any given case is thus to a large extent contingent on the unity of the international community, including the five permanent members with their veto powers.
Likewise, the processes to determine (non-)compliance are complex and multifaceted, and they depend on technological as well as political factors. Scientific and technological developments can present challenges if they increase proliferation risks and complicate verification of compliance. However, they can also provide additional opportunities, for example by improving detection methods or facilitating verification of compliance in other ways. Processes to determine (non-)compliance will usually be based on scientific and technological assessments, so it is important that there are sound measures in place and that relevant scientific and technological developments are taken into consideration as much as possible. However, compliance assessments, as well as decisions to establish new or implement existing compliance and enforcement measures, are ultimately political decisions that take place in political, often polarised, settings. One example is the discussions about verification in the BWC. This topic is back on the official BWC agenda after a 20-year hiatus, but political disputes and geopolitical tensions are severely inhibiting the chances of success. The case of Iran’s nuclear programme is another case in point. Moreover, disinformation and attempts to undermine trust in technological assessments may complicate compliance discussions, as has been the case for several years when it comes to the OPCW’s ability to deal with chemical weapons use. Especially in the current challenging international security climate, in which the chances of pursuing cooperative approaches to disarmament and non-proliferation seem to be constantly on the decline, it will be important to preserve, enhance and apply the measures that are already in place, and to continuously explore new ways of ensuring and enhancing compliance with and enforcement of non-proliferation and disarmament obligations.