What drives states to join universal WMD treaties

Our understanding of WMD treaties is largely based on what we know about the nuclear Non-Proliferation Treaty (NPT). In a new article, Jan Karlas studies state participation in all 10 universal treaties. He finds that states ratify those treaties for a variety of reasons.

Currently, there are 10 universal treaties that were adopted since the end of the Second World War and regulate weapons of mass destruction (WMD). These treaties limit the possession or testing of nuclear weapons (nuclear weapons treaties), prohibit chemical and biological weapons (CBW treaties), and ban the deployment of WMD in Antarctica and outer space, and on the seabed (zonal treaties). Almost all of them came into being during the second half of the 20th century as a result of the convergence in the interests of the two nuclear superpowers, represented by the USA and the USSR, and the majority of the other states.

To be effective and legitimate, WMD treaties need be truly universal and involve ideally all sovereign states. However, they only hardly manage to reach this goal. Typically, a certain number of countries ratify a WMD treaty relatively quickly, others wait to ratify for a longer time, and some even do not become parties to it. For the example, the Biological Weapons Convention joined together more than 75% states only 31 years after its adoption, and at this moment, only 41% of states ratified the Seabed Treaty.

It is important to understand when states enter WMD treaties, and when they do so only with a considerable delay, or even stay outside a treaty. The neorealist theory of international relations would, in this regard, differentiate states on the basis of their security situations and capabilities. Those that face security threats and have the necessary capabilities to develop WMD should be more likely to keep their autonomy and postpone the ratification of WMD treaties. Those that are not confronted with security threats, or do not have the necessary capabilities, are more likely to join these treaties quickly. Several scholars used these ideas to explain the ratification of the most prominent WMD treaty, the Nuclear Non-Proliferation Treaty (NPT).

In my paper, I go beyond the NPT, seeking to explain what drives ratification decisions generally, in relation to all the categories of WMD treaties. I reconsider the costs and benefits from participation in the different categories of treaties, and formulate a new explanation for this participation. A statistical analysis that maps the ratification behaviour of 204 states during the years 1960-2022 confirms this explanation.

The findings of the paper show that there are four specific factors that determine propensity of states to commit to WMD treaties. First, the possession/pursuit of WMD delays participation in treaties that completely ban these weapons, or they testing (CBW treaties and the majority of nuclear weapons treaties). This finding has two non-trivial implications. The first of them is that by far not all states that live in insecure environments necessarily postpone the ratification of WMD treaties. At the same time, the majority of states that possess or pursue WMD do not immediately destroy them, or stop the effort to acquire them, once there is a new treaty that calls for it. They sometimes join such a treaty, but after a relatively long time.

Second, the attitudes of countries to the US-led, liberal hegemonic order influences their decisions on participation in nuclear weapons treaties. My findings show that when countries are satisfied with this order, they generally join nuclear weapons treaties quickly. This can be explained by the fact that the nuclear order, which most of these treaties support, is closely linked to the liberal hegemonic order. The preliminary data also shows that the countries that have critical views of the US-built order have been entering the recently adopted Treaty on the Prohibition of Nuclear Weapons, which, unlike other nuclear weapons treaties, challenges the hegemonic nuclear order, considerably more quickly than the states that are content with this order.

Third, economically developed states commit more quickly than less developed states to CBW treaties and zonal treaties. These treaties stipulate that states take necessary domestic legal and policy measures to regulate the use of biological and chemical materials, or set-up the basic rules for economic, scientific, and other activities taking place in Antarctica and outer space. The large biotechnological and chemical industries, and the resources needed for the exploration and exploitation of remote international spaces, increase the stakes that developed states have in the CBW and zonal treaties.

Fourth, the probability that a state will ratify any of the three categories of WMD treaties raises when a certain number of its regional peers joined it. When observing the positive ratification decisions of their peers, state representatives become more convinced that a given treaty represents a useful policy tool to strengthen national and international security. And they also react to the ratification decisions of their peers to act in line with the dominant preferences within their regional political community.

All these findings also imply that WMD treaties do not perform particularly well at identifying the states that comply with their provisions, simply because many countries join them with delays, or stay out of them, unless they have some benefits from participation. Due to this, these treaties do not work as ideal screening devices that would provide accurate information about states complying with the international rules on WMD. The lack of universal membership also limits their authority to provide legitimization to these rules.

Scholars suggested several ways that can ensure the widespread participation of states in WMD treaties and regimes. They argue that the most powerful states must act as leaders and provide incentives to smaller states, or that strong verification mechanisms must support treaties so that the participating states have information about the (non-)compliant behaviour. My paper identifies two additional important aspects. First, WMD treaties have a greater chance to reach a widespread membership if their functions provide substantial benefits to the different groups of states. Second, the existence of certain minimal numbers of states that support a WMD treaty in the individual world regions is another crucial precondition for its widespread ratification.

Jan Karlas is the author of “Explaining state participation in ten universal WMD treaties: A survival analysis of ratification decisions”, Contemporary Security Policy, which can be accessed here.

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