The Resolution 3472 B (1975) of the United Nations General Assembly (UNGA) defines a NWFZ as:

"(...) any area, recognized as such by the General Assembly of the United Nations, which any group of States has established, in the free exercise of its sovereignty, by virtue of a treaty or convention by which:

1. The status of total absence of nuclear weapons to which that zone will be subject is defined, including the procedure for setting its limits;
2. An international verification and control system is established to guarantee compliance with the obligations derived from that statute.

The States that make up a NWFZ, in the exercise of their sovereignty, undertake to prohibit in their respective territories the research, design, development, testing, acquisition, deployment and possession of nuclear weapons.

Resolution 3472 B also includes a definition of the main obligations of nuclear-weapon States towards NWFZs and towards their member States:

"2. In any case of a nuclear-weapon-free zone that has been recognized as such by the General Assembly, all nuclear-weapon States must enter into or reaffirm, in a solemn international instrument that is fully legally binding, such as a treaty, a convention or a protocol, the following obligations:

1. Respect in all its parts the status of total absence of nuclear weapons defined in the treaty or convention that serves as the constitutive instrument of the zone;
2. Not contribute in any way to the practice of acts in the territories that are part of the zone that entail a violation of the aforementioned treaty or convention;
3. "Do not use nuclear weapons and do not threaten their use against the Member States of the zone."

The United Nations Disarmament Committee in its report of the April 30th 1999, recommended a series of principles and guidelines for the establishment of nuclear weapon-free zones, among others:

• NWFZs must be established on the basis of agreements freely concluded between the States of the interested region.
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• The initiative to create a NWFZ must come exclusively from the States of the region in question and be carried out by all the States of that region.
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• In cases where there is consensus on the objective of establishing a NWFZ in a given region, the international community should encourage and support the efforts of States in the region concerned to establish such a zone. 
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• As appropriate, the States in the region concerned should be provided with the assistance they need in their efforts to establish a nuclear-weapon-free zone, drawing, in particular, on the essential role played by the United Nations.
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• All States of the region concerned must participate in the negotiations relating to the zone and its establishment in accordance with agreements or arrangements freely concluded between the States of the region.
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• The status of a NWFZ must be respected by all States parties to the treaty establishing the zone as well as by States outside the region, including all States whose cooperation and support are essential for the zone to have as effective as possible, namely the States possessing nuclear weapons and, if there are any, the States that have territories or that are responsible, by international commitments, for territories located in the area in question.
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• Nuclear-weapon States should be consulted during negotiations on each treaty establishing a NWFZ, and its relevant protocols, in order to facilitate the signature and ratification by those States of the relevant treaty protocols under which must undertake legally binding obligations regarding the status of the area and not to use or threaten to use nuclear weapons against the States parties to the treaty.
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• In the event that there are States that have territory or that are internationally responsible for territories within the area in question, these States must be consulted during the negotiations on each treaty establishing a NWFZ and on its relevant protocols, with with a view to facilitating the signing and ratification, by those States, of the relevant protocols.
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• Any treaty establishing a NWFZ should provide for the effective prohibition of the development, manufacture, control, possession, testing, placement or transportation by States Parties of any type of nuclear explosive device, for any purpose, and stipulate that The State Parties will not allow any other State to place nuclear explosive devices in the area.
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• Any treaty establishing a NWFZ should provide for effective verification of compliance with the obligations of the parties to the relevant treaty, inter alia, through the application of the full safeguards of the International Atomic Energy Agency to all activities. nuclear in the area.
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• The existence of a NWFZ should not prevent the use of nuclear science and technology for peaceful purposes; At the same time, as long as they were provided for in the treaties by which said zone had been established, it could promote bilateral, regional and international cooperation activities for the peaceful use of nuclear energy in the zone, in support of socioeconomic, scientific and economic development. technological of the States parties.
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In 1967, with the opening for signature of the Treaty for the Prohibition of Nuclear Weapons in Latin America and the Caribbean (Treaty of Tlatelolco), the first NWFZ was established in a permanently populated territory on the planet.

The Latin American and Caribbean initiative inspired the establishment of four other NWFZs: South Pacific (Raratonga Treaty, 1985); Southeast Asian (Bangkok Treaty, nineteen ninety five); Africa (Treaty of Pelindaba, nineteen ninety six); Central Asia (Central Asian Treaty, 2006) and the territory of Mongolia, which in 2000 obtained international recognition as a Nuclear Weapon Free State (Resolution 55/335 S of the UNGA).

• Treaty of Tlatelolco: Establishes the Latin American and Caribbean NWFZ. It was opened for signature on February 14, 1967, and entered into force on April 25, 1969. It has been ratified by all 33 states in the region: Antigua and Barbuda, Argentina, Bahamas, Barbados, Belize, Bolivia, Brazil, Chile, Colombia, Costa Rica, Cuba, Dominica, Dominican Republic, Ecuador, El Salvador, Grenada, Guatemala, Guyana, Haiti, Honduras, Jamaica, Mexico, Nicaragua, Panama, Paraguay, Peru, Saint Kitts and Nevis, Saint Lucia, Saint Vincent and the Grenadines, Suriname, Trinidad and Tobago, Uruguay, and Venezuela. The Treaty of Tlatelolco contains two Additional Protocols. Protocol I is intended for extraterritorial states that de jure o de facto have territories under their responsibility in the Treaty Application Zone. It has been signed and ratified by the United States, France, the Netherlands and the United Kingdom. For its part, Additional Protocol II is aimed at nuclear weapon states. It has been signed and ratified by China, the United States, France, the United Kingdom and Russia.
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