Heading the Wrong Way? Japan and the Growing Nuclear Threats in Northeast Asia
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Heading the Wrong Way? Japan and the Growing Nuclear Threats in Northeast Asia


APLN member Tatsujiro Suzuki analyses the impacts and consequences of Japan’s new military-oriented policies and offers a way forward. The original article is on the Global Asia website.

THE RUSSIAN invasion of Ukraine in February 2022 raised security concerns not only in Europe but also in Northeast Asia. In particular, the invasion came with veiled threats by Russia to use nuclear weapons. This generated serious concern that nuclear weapons could be used for the first time since 1945, when Hiroshima and Nagasaki were attacked with atomic bombs. In Northeast Asia, there are four nuclear-armed countries — the United States, Russia, China and North Korea — and possible use of nuclear weapons is no longer considered hypothetical. Japan, along with South Korea, has depended on “extended nuclear deterrence” provided by the US, but the latter is now seriously considering a strengthening of the nuclear umbrella as well as possibly acquiring its own nuclear defense capability. Japan, meanwhile, is maintaining its non-nuclear policy. But is Tokyo’s new, more aggressive security policy heading in the right direction? What are the possible impacts and consequences of these new military-oriented policies? I will try in this essay to answer these questions while exploring possible alternative approaches for Japan.




The North Korean threat: On Sept. 8, 2022, North Korea adopted a new law on nuclear weapons that suggests a shift in the country’s policy on them.​1 Kim Jong Un stressed in a speech on the law that “advancement of nuclear forces is irreversible” and that it is now “impossible to denuclearize.” The law specifies five cases where North Korea might use nuclear weapons. It suggests that they could be used against conventional attacks, implying that a first use of nuclear weapons is also now possible. The five cases imply that the role of nuclear weapons in North Korea’s security policy has expanded significantly, which means that the risk of nuclear weapons use is now much higher than in the past. The law also emphasizes the role of tactical nuclear weapons, which could be used against South Korea and Japan. In short, the new law makes clear that North Korea now has a much more aggressive nuclear strategy.
Along with this new nuclear policy, North Korea’s missile capabilities have also expanded rapidly. In 2022, North Korea conducted more than 95 missile tests, by far the largest number yet (the previous largest number was 24, in 2017).2 On March 13 of this year, North Korea launched two “strategic cruise missiles” from a submarine for the first time. It was reported that the missiles “precisely hit” a target in the Sea of Japan and traveled about 1,500 kilometers, which is far enough to hit US bases in Japan.3 Although North Korea has not tested a nuclear device since 2017, there are concerns that it could conduct its seventh such test soon.4 If that happens, nuclear tensions in the region will inevitably escalate.

The China Threat:
 It is estimated that China has approximately 410 nuclear warheads as of 2022, and its nuclear weapons programs seem to be expanding very rapidly.5 According to a report by the US Department of Defense, the number of Chinese nuclear warheads may increase to 1,000 by 2030 and 1,500 by 2035.6 In order to achieve these goals, China needs fissile materials (highly enriched uranium and plutonium) for nuclear weapons. Its current stockpile of fissile materials is estimated to be insufficient to achieve these goals.7

One important issue is China’s civilian nuclear power program, which may be connected to its nuclear-weapons program. China is currently planning to build two reprocessing plants that can recover plutonium from spent nuclear fuel. The first is expected to begin operations from around 2025 and the second from around 2030. In addition, China is building two fast breeder reactors (FBRs) that could produce super-grade plutonium for nuclear weapons. If both the FBRs and reprocessing plants are completed, China’s plutonium production capability will increase dramatically. It is estimated that a maximum of 330 kilograms of super-grade plutonium could be produced per year, adding to the current stockpile of 2.9 tons. If this plutonium is diverted to nuclear weapons, China may have enough plutonium for 1,000 nuclear weapons or more.8

This has sensitive implications for Japan, which has a large reprocessing plant and has already accumulated more than 45 tons of separated plutonium (reactor-grade). While all Japanese nuclear facilities and nuclear materials are under international safeguards, China’s nuclear facilities and nuclear materials do not fall under international safeguard agreements. It is crucially important for the international community that China accepts international safeguards and that civilian nuclear materials are not diverted to nuclear weapons use.



In responding to growing nuclear threats from North Korea and China, Japan’s top priority has been to ensure that the US extended nuclear deterrence would not be compromised. It is the same for South Korea. On Nov. 13, 2022, the top leaders of the US, South Korea and Japan issued a joint statement emphasizing strengthening extended nuclear deterrence: “President Biden reiterated that the US commitment to defend Japan and the [Republic of Korea] is ironclad and backed by the full range of capabilities, including nuclear. As the regional security environment grows more challenging, President Biden reaffirms that the US commitment to reinforce extended deterrence to Japan and the ROK will only strengthen.”9

Japan, South Korea and the US have also strengthened their joint military drills. For example, on Feb. 22 this year, the navies from the three conducted a rare joint exercise after North Korea fired a long-range missile into Japan’s exclusive economic zone off Hokkaido.10 Japan’s Ground Self Defense Force and US Marines held joint military exercises on the island of Tokunoshima in Kagoshima Prefecture designed to simulate defending and recapturing remote islands.11 This was an apparent warning to China against possible military action involving remote islands.

The Japan-US Extended Deterrence Dialogue was established in 2010 to make sure the credibility of extended deterrence provided by the US remains solid. But after the Russian invasion of Ukraine, the credibility of extended deterrence has suddenly become a major domestic policy issue both in South Korea and Japan, leading to calls for a NATO-type “nuclear sharing scheme” as well as re-deployment of tactical nuclear weapons in South Korea (which will be discussed later). In order to respond to such concerns, a recent study by a US think tank recommended the creation of a new framework for joint nuclear planning, similar to NATO’s planning group.12




In addition to strengthening extended deterrence, the Japanese government is bolstering its own defense capabilities. In December 2022, it issued a new “National Security Strategy for Japan,” which is considered a significant change in Japan’s self-defense policy. It lays out the following: “In order to respond to this security environment, Japan will fundamentally reinforce its defense capabilities… Japan will respond to situations in a multi-layered way by cross domain operational capabilities that enhance the Japan Self-Defense Forces (SDF) capabilities overall, through the synergy of organically integrated capabilities in space, cyberspace, and electromagnetic domains as well as in ground, maritime and air, and by stand-off defense capabilities and other capabilities that will enable us to respond to invading forces from outside the sphere of threats … For this reason, we need counterstrike capabilities: capabilities which, in the case of missile attacks by an opponent, enable Japan to mount effective counterstrikes against the opponent to prevent further attacks while defending against incoming missiles by means of missile defense network” (emphasis added).13
This new policy of adding counterstrike capability has raised domestic debate over whether it is within existing “exclusively defense-oriented policy” under Japan’s peace constitution. The Japanese government has already submitted a new budget increase of 56 percent from 27.5 trillion yen (US$210 billion) to about 43 trillion yen over five years.14

This budget increase and the strengthening of Japan’s defense forces seems to be at least partially accepted by the Japanese public. According to a recent public survey done by the Cabinet Office, 41.5 percent of respondents are in favor of expanding the capabilities of the Self-Defense Force, which is the highest figure in the survey’s history. Meanwhile, 53 percent of respondents are in favor of maintaining the current level.15 But a majority of the public is still in favor of diplomatic solutions rather than military force. According to a separate public opinion poll, 60 percent of respondents are in favor of sticking to “exclusively defense-oriented policy” and 32 percent are in favor of diplomatic solutions, while only 15 percent are in favor of an offensive military buildup. The same public opinion polls suggest that 48 percent of the public is concerned that Japan may be dragged into a war by other countries.16



As noted above, the credibility of extended nuclear deterrence has become a major domestic issue both in Japan and South Korea. President Yoon Suk-yeol suggested that South Korea could pursue its own nuclear weapons, and Seoul Mayor Oh Se-hoon said it needs an “active nuclear umbrella” or “its own nuclear weapons.” These statements reflect strong public support for acquiring nuclear weapons, which is at around 60-70 percent. But so far, such high public support has not led to an actual policy shift in South Korea.17

In Japan, former Prime Minister Shinzo Abe’s remarks on a TV program in February 2022, stating that “Japan needs to discuss the option of a NATO-style nuclear-sharing agreement with the US,” triggered debate in Japan.18 But Prime Minister Fumio Kishida quickly rejected the idea because it may violate the “three non-nuclear principles” (not to manufacture, not to own and not to bring in nuclear weapons).19 Public opinion seemed to support Kishida’s policy. According to a poll conducted by the Japan Association for Public Opinion Research, 56 percent of respondents are against “proceeding the discussion on nuclear sharing,” while only 20 percent are in favor. The same public opinion poll shows 61 percent of respondents are in favor of Japan’s ratification of the Treaty on the Prohibition of Nuclear Weapons (TPNW).20

In short, despite strong public support for nuclear weapons in South Korea, both the Japanese public and government are still in favor of a non-nuclear policy. However, the Japanese government is opposing the idea of joining the TPNW, mainly due to its dependence on extended nuclear deterrence.




While Japan’s commitment to a non-nuclear policy remains strong, its current security policy is increasingly dependent on extended nuclear deterrence, which could in turn increase tensions in the region. Is there any alternative? The following are some suggestions.

Reduce nuclear risk:
 While Japan can continue its policy of dependence on nuclear deterrence, it could still pursue policies to reduce nuclear risk and reduce its dependence on nuclear deterrence. For example, Tokyo could strongly support the joint statement made by five nuclear weapons states on “Preventing Nuclear War and Avoiding an Arms Race,” in which all five leaders affirmed that “a nuclear war cannot be won and must never be fought.”21

Another possibility is to support a “no first use” or “sole purpose” nuclear policy. On Aug. 9, 2021, five US organizations and 21 US nuclear-weapons policy experts sent a letter to then Japanese Prime Minister Yoshihide Suga and leaders of the main Japanese political parties, calling on Japan not to oppose a move by the US to adopt a no-first-use policy.22 The US Nuclear Posture Review eventually did not adopt such a policy, primarily due to opposition from allies including Japan.23 It is certainly worth trying to discuss the pros and cons of a no-first-use policy, which could reduce the risk of nuclear weapons use significantly.

Dialogue and confidence building:
 A second alternative is to reduce tensions through diplomacy, i.e. a dialogue among states in the region aimed at the denuclearization of the Korean Peninsula. But it should be remembered that in 2017 the tension between North Korea and South Korea/US was the highest in decades, before the two historic summit meetings were held in April and June 2018. If we do not take any diplomatic actions, tensions will never be reduced, while the delicate balance of deterrence could be broken at any time. Japan, along with South Korea, should ask the US to resume diplomacy with North Korea, involving China, to pursue the goals of the 2018 agreements between North Korea and South Korea as well as agreements between the US and North Korea. This year is also the 70th anniversary of the Korean Armistice Agreement in 1953 and an opportune time to resume the dialogue to finally end the Korean War.​

1 Jun Bong-geun, “Comparing North Korea’s Nuclear Forces Policy Laws,” Nov. 21, 2022, Asia Pacific Leadership Network for Non-proliferation and Disarmament (APLN), www.apln.network/analysis/commentaries/comparing-north-koreas-law-on-nuclear-forces-policy-2022-with-the-law-on-consolidating-the-position-of-nuclear-weapons-state-2013

2 Choe Sang-Hun, “Tracking North Korea’s Missile Launches,” The New York Times, March 15, 2023, www.nytimes.com/article/north-korea-missile-launches.html
3 Joseph Johnson, “North Korea launches missiles from submarine as US-South Korea military drills start,” The Japan Times, March 13, 2023; Choe Sang-Hun, “Tracking North Korea’s Missile Launches,” The New York Times, March 15, 2023, www.nytimes.com/article/north-korea-missile-launches.html
4 Ryo Kawamura, “US not ruling out North Korea’s nuclear test before early March,” Nikkei Asia, Feb. 11, 2023, asia.nikkei.com/Spotlight/N-Korea-at-crossroads/U.S.-not-ruling-out-North-Korea-s-nuclear-test-before-early-March
5 Hans M. Kristensen, Matt Korda, Eliana Reynolds, “Nuclear Notebook: Chinese nuclear weapons, 2023,” Bulletin of the Atomic Scientists, March 13, 2023, thebulletin.org/premium/2023-03/nuclear-notebook-chinese-nuclear-weapons-2023/#post-heading 
6 “Annual Report to Congress: Military and Security Developments Involving the People’s Republic of China 2022,” US Department of Defense, Nov. 29, 2022.
7 According to the estimate made by the International Panel on Fissile Materials and RENCA, China had 14 tons of HEU and 2.9 tons of plutonium as of the end of 2020. See fissilematerials.org/ www.recna.nagasaki-u.ac.jp/recna/topics/40809 
8 Yuki Kobayashi, “Satellite Image Analysis: China’s Plutonium Production and Nuclear Arms Expansion,” Sasakawa Peace Foundation (SPF), China Observer, Feb. 14, 2023, www.spf.org/spf-china-observer/en/eisei/eisei-detail004.html
9 “Phnom Penh Statement on Trilateral Partnership for the Indo-Pacific,” Chinese Ministry of Foreign Affairs, Nov. 13, 2022, www.mofa.go.jp/mofaj/files/100420434.pdf
10 Jesse Johnson, “Japan, South Korea and US stage rare joint naval drill after North Korean launches,” The Japan Times, Feb. 22, 2023, www.japantimes.co.jp/news/2023/02/22/national/us-japan-south-korea-trilateral-naval-drill/
11 “Japan-US joint military exercise simulates defending and recapturing remote islands,” The Japan Times, March 5, 2023. www.japantimes.co.jp/news/2023/03/05/national/gsdf-marines-joint-exercise-media/
12 John J. Hamre and Joseph S. Nye Jr, “North Korea Policy and Extended Deterrence,” Center for Strategic & International Studies, January 2023, www.csis.org/analysis/recommendations-north-korea-policy-and-extended-deterrence
13 “National Security Strategy of Japan,” Japanese Cabinet Office, December 2022 (provisional translation), www.cas.go.jp/jp/siryou/221216anzenhoshou/nss-e.pdf
14 Tim Kelly and Sakura Murakami, “Pacifist Japan unveils biggest military build-up since World War Two”, Reuters, Dec. 17, 2022, www.reuters.com/world/asia-pacific/pacifist-japan-unveils-unprecedented-320-bln-military-build-up-2022-12-16/
15 “Jieitai Kibo ‘Zokyo-o’ 41.5%, Kako Saiko, Naikakufu Yoron Chosa (41.5% in favor of ‘expanding SDF’s capability’, highest in history, Cabinet Office Public opinion survey),” Nihon Keizai Shimbun, March 7, 2023, www.nikkei.com/article/DGXZQOUA0684Q0W3A300C2000000/
16 “Saishin Seron Chosa: Senso-e-no Kikikan Takamaru (Latest Public Opinion Poll: Concern over War is Rising),” Nagasaki Shimbun, Aug. 1, 2022.
17 Conner Echols, “A supermajority of South Koreans want nukes: polls,” Responsible Statecraft, March 6, 2023, responsiblestatecraft.org/ 2023/03/06/a-supermajority-of-south-koreans-want-nukes-polls/
18 Sayuli Romei, “The legacy of Shinzo Abe: a Japan divided about nuclear weapons,” Bulletin of the Atomic Scientists, Aug. 24, 2022, thebulletin.org/2022/08/the-legacy-of-shinzo-abe-a-japan-divided-about-nuclear-weapons/
19 “Kishida Rejects Japan’s Participation in Nuclear Sharing,” Jiji News, Feb. 28, 2022, sp.m.jiji.com/english/show/18243
20 Nagasaki Shimbun, op. cit.
21 “Joint Statement of the Leaders of the Five Nuclear-Weapon States on Preventing Nuclear War and Avoiding Arms Race,” The White House, Jan. 3, 2022, www.whitehouse.gov/briefing-room/statements-releases/2022/01/03/p5-statement-on-preventing-nuclear-war-and-avoiding-arms-races/
22 “United States experts call on Japan not to oppose a US no-first-use policy,” NoFirstUse Global, Aug. 10, 2021, nofirstuse.global/2021/08/10/united-states-experts-call-on-japan-not-to-oppose-a-us-no-first-use-policy/
23 “Allies lobby Biden to prevent shift to ‘no first use’ of nuclear arms,” Nikkei Asia, Oct. 31, 2021, asia.nikkei.com/Politics/International-relations/Allies-lobby-Biden-to-prevent-shift-to-no-first-use-of-nuclear-arms
Image: iStock/y-studio
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