The Treaty of Tlatelolco is particularly important as the first of the regional nuclear-weapon-free zone treaties. Tlatelolco was concluded in 1967 and so predates the NPT. Today there are five regional NWFZ treaties: Tlatelolco (Latin America); Raratonga (South Pacific); Bangkok (SE Asia); Pelindaba (Africa); and Semipalatinsk (Central Asia). In addition there are three treaties that prohibit nuclear weapons in particular geographic areas: Antarctica; Outer Space; and the Seabed. And Mongolia has declared itself a single-state NWFZ.
More than 110 states are included in nuclear-weapon-free zone treaties. These states are all non-nuclear-weapon states party to the NPT, hence are prohibited from acquiring nuclear weapons in any case. But the NWFZ treaties serve an important purpose by prohibiting the stationing of nuclear weapons. They also exclude nuclear testing – helping to reinforce the moratorium on nuclear testing pending entry-into-force of the CTBT.
The treaties also have an important transparency and confidence-building function, e.g.: some have reporting provisions on matters relevant to the treaty; most have clarification procedures by which parties may request information from other parties; and most have procedures for special inspections. The treaties provide a substantial body of experience to draw on for potential new NWFZ treaties, e.g. in the Middle East; South Asia; and the Korean Peninsula.