The Non Proliferation act of 1968 was created to prevent the spread of nuclear weapons. 85 percent of the world’s countries signed it. Non nuclear countries agreed to not make or accept nukes from anyone. Countries that had them could not build or share them. The International Atomic Energy Agency was created by the UN to inspect countries to ensure nuclear facilities were operating under peaceful terms but the NPT hasn 't been entirely successful. India and Pakistan tested nukes in 1998 and Israel 's nuclear capability is an open secret. None of those countries signed the NPT in 1968. North Korea did sign the treaty in 1970 but violated it in the 1990s when it started developing nukes and more recently in 2006 when they tested one.
Iran also signed the NPT in 1970 but was ruled by a pro western monarch named Shah Mohammad Reza Pahlavi. He was overthrown in 1979 and fled the country. Soon after the Ayatollah Ruholla Khomiena who rejected western values and
Bibliography: Squassoni, S. (20 JUL 2006). Iran 's Nuclear Program: Recent Developments. Washington, D.C.: LIBRARY OF CONGRESS WASHINGTON DC CONGRESSIONAL RESEARCH SERVICE.