Skip to main content

Defining IND and its relation to other concepts

Monday 4 – Wednesday 6 March 2024 I WP3260


A clear, common definition of IND is lacking, although participants disagreed if there is even a need for a definition. There is support for moving towards a common understanding, but having one, narrow definition could be limiting. Discussions on defining IND can be constraining and prove to be distracting from progress on IND-related issues; however, in spite of these reservations, there was progress on building a common understanding of IND and how it links to other concepts.

Irreversibility is a spectrum. It can be enhanced, but nothing is every truly irreversible. For example, nuclear capacity cannot go to zero, but weapons can be irreversibly eliminated in a verifiable manner. Thus, judgements of irreversibility are subjective and are closely linked to trust and confidence.

Despite the progress made at this dialogue, there is still work to be done on building a common understanding in a number of areas, including in IND’s relationship to delivery vehicles and the concept of “complete” disarmament. Further conversations were had regarding IND’s relationship to the concepts of verification, transparency and latency.


Verification of IND does need a narrow definition as it differs from current, traditional discussions around verification. While IND and verification do overlap, they differ in scope and outcomes, and, therefore, should not be conflated as IND covers a broader set of items often not covered by treaties.

The community needs to be explicit about what is being verified: does this mean changes of physical material, facilities or something else? Further, there is a difference between verifying that something is irreversible and verifying that an action that has happened is not being undone.


Transparency was linked a number of times to IND, especially as it can help lead to greater trust, confidence and cooperation. It can help foster a virtuous action cycle where States continue to take cooperative measures towards IND via transparent actions.

Linkages between irreversibility, verification and transparency are important to explore and develop a common understanding of as they are the three key principles established in the 2010 NPT RevCon.[4]


Latency is in some ways the reverse image of irreversibility, and is thus also a spectrum. Determining what contributes to a State’s latency (or latent capability in the case of formerly-armed States) can help inform the IND regime of which specific areas should be considered for verification and monitoring in a disarming or disarmed world.

Some States think of latency as a deterrent in and of itself, which allows for some security during the process of disarmament; however, this goes against the disarmament norm, which calls for the reduced importance of nuclear weapons.

Discussions on hedging can be conflated with discussions on latency, but they should be separated as hedging requires active decisions. Further, some participants were hesitant to include latency as part of irreversibility conversations as the topic can distract and prove contentious, thus hampering collaborative progress on IND.

[4] “Final Document – Volume I (NPT/CONF 2010/50 (Vol. I))”, 2010 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons, 2010, p.20, in


Executive Summary – IND 2024


IND and the process of achieving disarmament

Want to find out more?

Sign up to our newsletter