Is the NPT unraveling? Evidence from text analysis of review conference statements

The Treaty on the Non-Proliferation of Nuclear Weapons (NPT) is a landmark international treaty that is widely regarded as a cornerstone of the global nuclear non-proliferation regime. However, pessimists point to a growing divergence of preferences between nuclear weapons states and non-nuclear weapons states as a precursor to the impending ‘unraveling of this vital piece of international law’. In this article, we test for evidence of preference divergence using statements from NPT review conferences, which are manifestos presenting each country’s position on the NPT. We measure preferences on the NPT using Wordfish, a method that is frequently used to estimate ideological preferences from election manifestos. Our measure estimates the latent positions of state actors along a ‘non-proliferation vs. disarmament’ dimension, and shows little evidence of growing preference divergence between the nuclear weapons states and non-nuclear weapons states. Thus, a significant premise underlying more pessimistic assessments of the NPT appears to be in doubt.