Practical Implementation of the Join-and-Disarm Option in the Treaty on the Prohibition of Nuclear Weapons

The Treaty on the Prohibition of Nuclear Weapons provides a nuclear-armed state that joins the treaty with two options. One is to join after eliminating its weapons and nuclear-weapon program. Alternatively, the state can join the treaty while still possessing nuclear weapons. In this case it must eliminate its weapons in accordance with a time-bound plan approved by the state parties. This option, known as “join and disarm,” provides the disarming state with an opportunity to join the treaty immediately after making the decision to do so and to complete disarmament within a defined time frame. However, it also creates a challenge for the verification program, which has to find a way to protect proliferation-sensitive information about nuclear weapons. This article suggests a verification arrangement that does not require access to sensitive information during the weapons elimination process. This is achieved by containing nuclear weapons and all dismantlement activities in a dedicated segment of the nuclear complex of the disarming state. The only information the disarming state releases at the start of the process is the total amount of fissile materials placed in the segment. The dismantlement of weapons is verified by accounting for the fissile materials that are removed from the segment in unclassified forms.