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An American Analysis of Japan’s Nuclear Options

How can Japan defend itself against China and North Korea? An American analysis of an effective nuclear deterrence for Japan remains relevant 40 years later.



A nuclear-powered Type 094A Jin-class ballistic missile submarine of the Chinese People's Liberation Army (PLA) Navy. China’s submarines have been caught prowling in Japanese waters and along the border of Japan’s territorial sea. REUTERS/Stringer

How would the United States react to the idea of Japan’s nuclear armament?

Russian President Vladimir Putin declared on February 27 that Russia was activating its nuclear deterrence forces in the process of its invasion of Ukraine. This demonstrates that the threat of nuclear force is still a factor in international conflicts.

Japan faces a real nuclear threat to its national security. Chinese authorities permitted the distribution of a video simulating a nuclear attack on Japan in the event of a Taiwan contingency. Moreover, North Korea stated that Pyongyang would sink the Japanese archipelago to the bottom of the sea with its nuclear weapons. It is natural for Japan to begin a discussion on its own nuclear deterrence in self-defense.

Japan has been dependent on the United States for its extended nuclear deterrence. What if Japan seeks to possess its own nuclear defenses? How would the United States react to the idea of Japan’s nuclear armament?

In this regard, it is instructive to recognize that, as early as the 1980s, a thesis on Japan’s nuclear armament was being widely discussed in the US policy community. Its content has been little known in Tokyo, but this paper could now provide guidance for the current nuclear debate in Japan. 

Nimitz-class aircraft carrier USS Carl Vinson (CVN 70) and other naval vessels with the Japan Maritime Self-Defense Force (JMSDF) vessels, Sept. 19, 2021. (Haydn N. Smith/U.S. Navy via AP)

This thesis was written by Colonel John E. Endicott of the US Air Force in 1975 and was titled, Japan’s Nuclear Option. At the time the discussion erupted in the early 1980s, he was associate dean of the National War College. Earlier, he had held several important positions in the international field in the Department of Defense, and before that served with the US Air Force in Japan.

His thesis began with a supposition that there was no longer an American nuclear umbrella for Japan. He commented on the topic in an early 1980s interview on the Soviet Union’s nuclear threat against Japan, issued in response to then-Prime Minister Yasuhiro Nakasone’s characterization of Japan as an “unsinkable aircraft carrier.” Endicott posited that Japan had no recourse but to develop its own nuclear deterrence, other than total surrender.

Colonel Endicott’s thesis suggested specific means Japan might use to deter a Soviet nuclear attack or threat of attack on Japan, and why:

  • If the prospect is clear that approximately 25% of the population in major parts of the Soviet Union would be destroyed by Japan’s nuclear retaliation following the Soviet Union’s initial nuclear weapons attack on Japan, then the Soviet Union could not afford to attack Japan in the first place.
  • Japan would have three options to possess sufficient nuclear power to inflict that much damage on the Soviet Union: intercontinental ballistic missiles, strategic bombers, and strategic submarine fleet armed with submarine-launched ballistic missiles (SLBMs). Of the three types, the submarine would be the most viable. 

With the Soviet Union’s invasion of Afghanistan in 1980, the US-Soviet confrontation level had reached a perilous peak. The Soviet threat to Japan was also real.

Endicott hypothesized that the Soviets would launch a first strike on Japan using nuclear weapons. Japan’s nuclear deterrence in that context meant having the ability to withstand a first strike and then the capability to retaliate by inflicting unacceptable destruction on the Soviet Union.

The most critical assertions made by the paper were:

  • Japan should have 10 nuclear-powered submarines with nuclear missiles similar to the US Navy’s Polaris class.
  • Each submarine should be equipped with 16 nuclear warhead missiles with a range of over 4,600 km.
  • Four to six of those vessels should be deployed in and around the Arabian Sea at all times.
  • Japanese submarines deployed in the Arabian Sea should be able to launch up to a maximum of 96 nuclear missiles at 25 major cities in the Soviet Union, including Moscow.

Even considering the Soviet side’s anti-ballistic missile capabilities, the Soviet Union would likely assess that this strategy could cause unacceptable damage.

The paper thus concluded that Japan could deter the Soviet Union’s nuclear threat, and that nuclear armament of Japan was possible. However, Colonel Endicott added that he himself was against Japan’s nuclear armament at that point. 

Today, 40 years later, these assumptions still appear effective for nuclear deterrence against China and North Korea. They also illustrate that the United States, our only ally, has been studying Japan’s potential for nuclear armament for decades.


(Read the article in Japanese at this link.)

Author: Yoshihisa Komori

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