Non-Proliferation Treaty (NPT)

The Treaty on the Non-Proliferation of Nuclear Weapons, opened for signature in 1968 and entered into force on 5 March 1970, with 191 states parties. It bars non-nuclear-weapon states from acquiring nuclear weapons, commits the five recognized nuclear-weapon states to disarmament negotiations (Article VI), and guarantees access to peaceful nuclear energy under IAEA safeguards. It anchors the legal basis cited in WMD-interdiction operations and proliferation-related sanctions, since transfers contrary to it underpin designations and inspections.