The NPT consists of a preamble and eleven articles. Although the concept of "pillars" is not expressed anywhere in the NPT, the treaty is nevertheless sometimes interpreted as a three-pillar system, with an implicit balance among them:
# disarmament, and
# the right to peacefully use nuclear technology.
The NPT is often seen to be based on a central bargain: “the NPT non-nuclear-weapon states agree never to acquire nuclear weapons and the NPT nuclear-weapon states in exchange agree to share the benefits of peaceful nuclear technology and to pursue nuclear disarmament aimed at the ultimate elimination of their nuclear arsenals”. The treaty is reviewed every five years in meetings called Review Conferences of the Parties to the Treaty of Non-Proliferation of Nuclear Weapons. Even though the treaty was originally conceived with a limited duration of 25 years, the signing parties decided, by consensus, to extend the treaty indefinitely and without conditions during the Review Conference in New York City on May 11, 1995.
At the time the NPT was proposed, there were predictions of 25-30 nuclear weapon states within 20 years. Instead, over forty years later, only four states are not parties to the NPT, and they are the only additional states believed to possess nuclear weapons. Several additional measures have been adopted to strengthen the NPT and the broader nuclear nonproliferation regime and make it difficult for states to acquire the capability to produce nuclear weapons, including the export controls of the Nuclear Suppliers Group and the enhanced verification measures of the IAEA Additional Protocol. However, critics argue that the NPT cannot stop the proliferation of nuclear weapons or the motivation to acquire them. They express disappointment with the limited progress on nuclear disarmament, where the five authorized nuclear weapons states still have 22,000 warheads in their combined stockpile and have shown a reluctance to disarm further. Several high-ranking officials within the United Nations have said that they can do little to stop states using nuclear reactors to produce nuclear weapons.