• Research
  • Emissary
  • About
  • Experts
Carnegie Global logoCarnegie lettermark logo
DemocracyIran
  • Donate
{
  "authors": [
    "Se Young Jang"
  ],
  "type": "other",
  "centerAffiliationAll": "dc",
  "centers": [
    "Carnegie Endowment for International Peace"
  ],
  "collections": [
    "Korean Peninsula"
  ],
  "englishNewsletterAll": "ctw",
  "nonEnglishNewsletterAll": "",
  "primaryCenter": "Carnegie Endowment for International Peace",
  "programAffiliation": "NPP",
  "programs": [
    "Nuclear Policy"
  ],
  "projects": [],
  "regions": [
    "East Asia",
    "South Korea"
  ],
  "topics": [
    "Nuclear Policy"
  ]
}

Source: Getty

Other

Bringing Seoul into the Non-Proliferation Regime

Pressure by the United States was less decisive in forcing South Korea to ratify the NPT in 1975 than commonly assumed.

Link Copied
By Se Young Jang
Published on Sep 20, 2017
Program mobile hero image

Program

Nuclear Policy

The Nuclear Policy Program aims to reduce the risk of nuclear war. Our experts diagnose acute risks stemming from technical and geopolitical developments, generate pragmatic solutions, and use our global network to advance risk-reduction policies. Our work covers deterrence, disarmament, arms control, nonproliferation, and nuclear energy.

Learn More

Source: Wilson Center

The Effect of ROK-Canada Reactor Deals on Korea's Ratification of the NPT

In this Nuclear Proliferation International History Project (NPIHP) Working Paper, Se Young Jang challenges the the common narrative that US pressure forced South Korea to ratify the NPT in 1975. Using new evidence from international archives, Jang finds that the decisive pressure came from a different country—Canada.

Key Findings

Pressure by the United States was less decisive in forcing South Korea to ratify the NPT in 1975 than commonly assumed. Records show that a consensus to ratify the treaty was reached within the ROK government by early March 1975—before the US applied meaningful pressure.

  • Although the US Embassy in Seoul forwarded its suspicions of the ROK’s nuclear ambitions during 1974, the inter-agency intelligence assessment concluding that the ROK had launched a nuclear weapons program was completed only in late February 1975. While the White House was still determining its response to the report, the ROK government had already decided to ratify the NPT up to the level of the Prime Minister.
  • In January 1975, the State Department confirmed that no specific actions had been taken to make the NPT ratification a condition for any US dealings with South Korea.

There is little evidence that the 1975 Congressional resolution calling on the EX-IM bank to defer financing for reactor construction in Korea had an impact on ROK decision-making. The short time between the introduction of the resolution to the Senate Committee on Foreign Relations on March 7th and the notification of ROK President Park’s decision to ratify the NPT by the Korean Ministry of Foreign Affairs on March 8th suggests the events were not directly related.

South Korea joined the NPT to secure the sale of Canadian heavy-water reactors, whose sale had been made contingent on ratification. The ROK government chose to pursue the plutonium route to a bomb in 1972, making the acquisition of heavy-water reactors critical to the entire project.

  • Evidence from Korean and Canadian archives show that the strengthened safeguards Canada placed on its nuclear reactors after the May 1974 Indian nuclear test played a decisive role in South Korea’s decision to ratify the NPT.
  • South Korea’s Foreign Minister first mentioned that Korea might consider ratifying the NPT if it were a precondition for the sale of a CANDU reactor during his visit to Ottawa in November 1974.
  • On January 20, 1975, Canada announced that they would reconsider the sale of reactors if South Korea refused to ratify the NPT. Three days later, ROK ministers recommended that President Park Chung Hee accept the Canadian ultimatum to secure the sale of two heavy water reactors (CANDU and NRX). Park approved the decision on March 7, 1975.
  • In December 1975, Canadian Secretary of External Affairs also asserted that South Korea had ratified the NPT upon Canada’s suggestion.

The South Korean government did not regard NPT ratification as the end of its military nuclear pursuits. South Korea’s program was not formally suspended until December 1976—over one-and-a-half years after the Korean National Assembly ratified the NPT in March 1975.

  • ROK officials still regarded the import of a NRX reactor to be possible at the time they chose to ratify the NPT under Canadian pressure. However, archival records show that Canadian officials saw any future sale of a NRX reactor to be unlikely.
  • South Korea’s negotiations with France to acquire a nuclear reprocessing facility continued even after the ROK ratified the NPT. US and Canadian concerns over the French reprocessing deal would stall the sale of Canadian reactors until 1976.

This paper was originally published by Nuclear Proliferation International History Project at Wilson Center

Read the paper

About the Author

Se Young Jang

Former Nonresident Scholar, Nuclear Policy Program

Se Young Jang was a nonresident scholar in the Nuclear Policy Program at the Carnegie Endowment for International Peace.

Se Young Jang
Former Nonresident Scholar, Nuclear Policy Program
Nuclear PolicyEast AsiaSouth Korea

Carnegie does not take institutional positions on public policy issues; the views represented herein are those of the author(s) and do not necessarily reflect the views of Carnegie, its staff, or its trustees.

More Work from Carnegie Endowment for International Peace

  • Black-and-white photo of the nuclear cargo ship NS Savannah.
    Commentary
    Emissary
    A Nuclear Odyssey at Sea

    Nuclear and maritime communities face a long and challenging journey to deploy commercial nuclear applications at sea. 

      Jamie Kwong, Toby Dalton

  • Japanese troops take part in a counter-landing live fire exercise as part of the annual Balikatan joint military drills on May 04, 2026 in Laoag, Ilocos Norte province, Philippines.
    Article
    The Two Logics Driving Japan’s Security Policy

    Japan’s revision of its three strategic documents reflects an intention to keep the United States engaged in the region while Japan fills any vacuums of U.S. power to preserve the Indo-Pacific order.

      • Ryo Sahashi

      Ryo Sahashi

  • Robot arm with disposable test tube virus sampling in laboratory
    Commentary
    Caught in the Middle: Chinese Biotech Firms’ Divergent Responses to U.S. Sanctions

    Chinese biotech companies have been on the receiving end of U.S. economic coercion. Yet their responses have differed significantly because firm and state interests are not uniformly aligned. For Washington, treating all Chinese tech firms the same, irrespective of their actual interests, risks pushing them farther into Beijing’s corner.

      Xue Gong

  • Two people in blue PPE standing over large metal rolls
    Commentary
    Emissary
    Inside the Global Race to Erode a Battery Manufacturing Monopoly

    Over the past decade, China has moved from marginal player to major producer of all things batteries. The United States, Europe, and others are aiming to balance the market.

      Milo McBride

  • Research
    Coercive Nuclear Threats Under Domestic Dissonance

    A look at how public opinion influences the credibility of coercive nuclear threats,and how it enables and constrains strategies of nuclear coercion.

      Lauren Sukin, Samuel Seitz

Get more news and analysis from
Carnegie Endowment for International Peace
Carnegie global logo, stacked
1779 Massachusetts Avenue NWWashington, DC, 20036-2103Phone: 202 483 7600
  • Research
  • Emissary
  • About
  • Experts
  • Donate
  • Programs
  • Events
  • Blogs
  • Podcasts
  • Contact
  • Annual Reports
  • Careers
  • Privacy
  • For Media
  • Government Resources
Get more news and analysis from
Carnegie Endowment for International Peace
© 2026 Carnegie Endowment for International Peace. All rights reserved.