North Korea's Nuclear History starts with the Korean War when the United States threated to use nuclear weapons as a means to end the Korean War.  Since then, the UN Security Council has worked to denuclearize the Korean Peninsula with a series of Resolutions, including Resolutions 1695, 1718, 1874, and 2087. The Six Party talks, consisting of North Korea, South Korea, China, Russia, Japan, and the United States, have also worked to reduce the nuclear presence in South Korea and North Korea. 
The nuclear program in North Korea started in the beginning of the 1950's, when North Korea started training personnel with the capabilities to build a nuclear program.  It started the Atomic Energy Research Institute in addition to the Academy of Sciences. In 1956, North Korea signed a joint treaty with USSR's Joint Institute for Nuclear Research, which strengthened their nuclear capabilities because North Korean scientists were able to go to the USSR for training.  Though North Korea received assistance from other nations in the development of their nuclear program, it remained largely independent from foreign influences.  Throughout the late 1900's, North Korea worked on developing its nuclear facilities for both civilian and military applications.  North Korea expanded the IRT-2000 research reactor and soon began building a 50NW nuclear reactor at what would be the heart of its nuclear operations, Yongbyon.  North Korea also agreed to sign the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) and the Joint Declaration on the Denuclearization of the Korean Peninsula at the beginning of the 1990's. 
In 1994, there was a crisis with North Korea when they refused to allow IAEA inspectors to analyze their plutonium production and reprocessing abilities.  North Korea also began to threaten to withdraw from the NPT if the U.S. or other nations threatened sanctions or retaliatory action.  Negotiations over the NPT dragged on until President Jimmy Carter traveled to the capital, Pyongyang, to meet with the North Korean leader.  The Agreed Framework was signed in 1994, which stated that North Korea would work towards Denuclearization of the Korean Peninsula. 
This would become a growing trend in relations with North Korea's growing nuclear prowess. North Korea is often suspected of conducting illicit activity, such as producing highly enriched uranium or reprocessed plutonium.  After being suspected of illegal activity, many countries will attempt to renew talks or agreements with North Korea to dissuade them from continuing on with nuclear development.  North Korea will often not engage in these talks until they are offered something in return, and will also threaten nuclear action if their needs are not heard. 
Since then, North Korea has conducted three known nuclear tests.  It was also began activity at the uranium enrichment plant in Yongbyon, in addition to restarting its 5MW graphite-moderated reactor.  There has also been extensive development in the water channels and dams connected to Yongbyon to build the secondary cooling system. Most recently, North Korea is believed to have tested a nuclear weapon around the beginning of the new year, but not enough information has been gathered to confirm the nature of the weapon tested. 
© Evelyn Xue. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 D. Wertz and M. McGrath, "North Korea's Nuclear Weapons Program," The National Committee on North Korea, January 2016.
 L. V. Sigal, Disarming Strangers: Nuclear Diplomacy with North Korea (Princeton University Press, 1997).
 S.-H. Choe, "North Korea Threatens to Conduct Nuclear Test," New York Times, 20 Nov. 14.