Nuclear Deterrence in Japan after the Invasion of Ukraine.

At the end of February 2022, the system of international security as guaranteed by the Vienna convention and United Nations was violated. Previous international agreements are once again put in question as to whether they can be trusted. Due to the Russian invasion, governments have a chance to reconsider their views on nuclear deterrence. For example, Japan and South Korea are already showing interest towards acquiring nuclear weapons stations on their own soil, which would strengthen the nuclear deterrence they are reliant on for their security. This article will analyze the steps Japan has been taking since the invasion of Ukraine in revising its stance on nuclear deterrence.

The Impact of War in Ukraine on the Credibility of International Treaties.

Russia’s invasion of Ukraine caused damage to the prestige of international law. While it could be previously surmised that international law is but a human construct and is not absolute, governments worldwide, since the end of the Second World War, tended to observe it. An open, inexcusable aggression against Ukraine by Russia goes against all the foundations of international law. [1]

The United Nations is unable to act on its mission of maintaining peace, as its structure allows Russia to veto any motion. [2] The Russian invasion of Ukraine is damaging not only to international law as an institution but has also irreparably damaged the UN’s credibility as the guarantor of international law and peace. The UN, founded on good intentions, currently lacks any power to act on its principles. In the eyes of governments, this could possibly mean a low drain of legitimacy away from the UN, stated to represent humanity as a whole on equal and respectful terms. Subsequently, the issue of legitimacy could push a number of law-abiding states in volatile regions to seek other, more tangible security guarantees. This has led to increased calls for reforming the UN. [3]

The Institute of treaties itself is, thus, put in question. A common, global agreement on the governance of the norms of international law over state relations seems to not have any significance when it comes to certain states. The international norms are therefore further undermined if countries, especially the major ones, do not abide by them.[4] Subsequently, governments have no solid guarantees that international law will be upheld by other parties. Coupled with the general lack of enforcement mechanisms, treaties have also always been conceptually flawed. Governments change and the following administrations can recede on their agreements, despite possible repercussions.

This can be illustrated through a practical case of Ukraine. More precisely, the inefficiency of the Budapest Memorandum signed in 1994, a treaty that was supposed to guarantee several countries’ security after the dissolution of the Soviet Union.

The Memorandum was signed by Russia, the U.S. and Great Britain and promised Belarus, Ukraine, and Kazakhstan security assurances. In exchange, the aforementioned countries were to give up the nuclear weapons on their soil in favour of Russia, which they’ve done.  Vladimir Putin’s Russia, however, has broken this promise – an internationally recognised treaty. [5] The treaty had insignificant weight in the eyes of Russian decision-makers. In the same vein, security alliances cannot truly guarantee a foreign country’s support in the wake of hostilities by a third party. The ongoing war could be used as an argument for the states to seek security guarantees outside of defensive alliances.

The fact that international law has repeatedly been unable to preserve peace is pushing countries in hostile geopolitical conditions to reconsider their previous stances on nuclear deterrence, as will be illustrated by Japan. This could lead to an undesirable shift towards militarisation and further securitisation of global politics, a reversal of the previous decades of strained peace. [6]

Japanese Nuclear Policy after the Invasion of Ukraine.

Nuclear weapons are widely recognised as evil by disarmament advocacy networks, while nuclear-armed states and their allies tend to evaluate nuclear weapons less critically. United Nations Secretary-General António Guterres, in his speech during an event to commemorate the International Day for the Total Elimination of Nuclear Weapons, had nothing but negative remarks about the existence of nuclear weapons.[7] Facilitating the elimination of nuclear weapons is one of the core UN aims. All states officially recognise the need to phase nuclear weapons out of arsenals, yet the ones who own them are significantly behind on their promises – the most prolific defence in favour of nuclear weapons is that “the time is not right”.

In June last year, the first conference of the Treaty on the Prohibition of Nuclear Weapons member states took place. The TPNW is a global peace initiative under the UN, aimed at outlawing nuclear weapons comprehensively, with no exceptions. Representatives of both domestic and international activist groups and NGOs, as well as states that are party to the treaty, convened in Vienna. They have reassured the world about their commitment to reach the “global zero” goal – total elimination of nuclear weapons.

The first meeting of the Treaty on Prohibition of Nuclear Weapons member states. Source: Flickr

One of the most numerous nuclear disarmament advocacy networks at the conference was represented by Japanese civil society groups. Japan, as the only country that has suffered the impact of a nuclear bombing, is against signing the TPNW, while being protected by the U.S. nuclear umbrella. This has been the status quo since the treaty was first proposed in 2011.  Tokyo is a peculiar case study, as, despite overwhelming public support for the treaty, the government is opposed to even legitimising the treaty by participating in it at least in the capacity of an observer. [8][9] The reason for this rigidity is pragmatic – Japan cannot both denounce nuclear weapons and remain under the U.S. nuclear umbrella. At the same time, when asked about the possible factors preventing Tokyo’s accession to the treaty, all NGOs have cited long-standing disputes in Northeast Asia, as well as already mentioned, Japan’s reliance on its military alliance with the United States. Due to the Russian belligerence, however, Japan now has an even stronger incentive to deepen its cooperation inside the defence pacts. Thus, NGOs expect Japan, a symbolic nuclear disarmament country, to ratify the TPNW as one of the last parties. [10]

Admittedly, Japan also has reasons to be wary of its neighbours. China and North Korea have been cited [11] as key geopolitical rivals for this country. Peking is lodging disputes against Japanese territories, causing great strain on their mutual relations. Pyongyang is a rogue state which is increasingly emboldened with incredibly dangerous, inexcusable missile tests. At least with Russia, Tokyo tried to retain friendly and cooperative relationships, if only to resolve the Kuril Islands dispute.

While previously open to negotiations, and regardless of their sincerity, Russia has frozen them due to Japan’s support of Ukraine since the invasion. [12] In an unprecedented decision, Tokyo has taken a solid, partial stance against Russian aggression and applied its own sanctions against Putin’s regime. Russia’s reckless belligerence culminated at an end to decades of efforts to foster a better relationship between the nations.

Late Japanese former prime minister Shinzo Abe, the country’s most prominent and hawkish politician in the 21st century, had previously tried to amend the peaceful constitution Japan has. His success was limited, and he could not reach the ultimate goal of amending the 9th Article, but he paved the way for the leading Japanese political party to continue amendment efforts. Abe’s beliefs also included an alarmingly open stance towards military nuclear capabilities. In one of his speeches, he proposed to consider exchanging the current U.S. nuclear umbrella for nuclear sharing [13], for which was the invasion of Ukraine cited as an impetus.

This decision would anger or concern every neighbour Japan has in the Pacific, adding to the overall volatility in the region. The difference can be understood through the importance of disarmament NGOs put on nuclear sharing and nuclear umbrellas. NGOs are pragmatically more invested in advocating in the countries where nuclear sharing is present, due to the physical presence of nuclear weapons.[14]

Regardless of the respect and influence which Abe has amongst the current leadership as a political figure, his stances should be expected to be in serious consideration by part of the Japanese political elite. Abe continuously promoted constitution revision with the aim to have Japan have an active army again. The incumbent Prime Minister Fumio Kishida and his government were closely tied to Shinzo Abe, and his legacy lives strong in their political aspirations. During Kishida’s New Year speech, he singled Abe’s assassination as one of the bigger events of 2022.[15] While Kishida has always been openly supportive of global nuclear disarmament and has rejected nuclear sharing [16], it’s impossible to say whether he will withstand the pressure of hardliner politicians in his party. Right now, Japan has started unprecedented re-militarisation efforts and a possible nuclear policy review is also on the table.

Former Prime Minister Shinzo Abe attended the plenary session of the House of Councillors, 2013. Source: Wikimedia

Japanese society’s reaction to the war in Ukraine.

Such a policy vector can be seen as justified by Japanese public opinion polls. The Russian invasion of Ukraine has strengthened beliefs amongst the population, that Japan should not only revise its constitution but also work towards obtaining better deterrence options, including nuclear sharing. [17] Many of the respondents from the Japanese population, especially older women, while not viewing war favourably, see no other option but to militarise beyond defence alliances to protect Japan from China.

When it comes to nuclear disarmament, the invasion of Ukraine has significantly raised the population’s sense of crisis. The Japanese branch of Lawyers Against Nuclear Arms NGO in its 2022 resolution indicates that the public support for the TPNW treaty has fallen by a whole ten per cent. From 71% in favour in 2021 to 61% in July 2022 [18], citing the invasion of Ukraine as the key factor for this shift.

Further changes in Japanese public opinion towards stronger security assurances could figuratively untie the hands of the politicians for legal changes. Introducing more nuclear weapons into Northeast Asia is not as worrying as the prospect of Tokyo normalising nuclear weapons further and even starting its own military nuclear program. As Japan is one of the most technologically advanced countries in the world with an extensive civil nuclear program, there is no doubt that it can develop its own nuclear weapons in a very short time. In 2004, this time has been estimated to be “in a matter of months”. [19] Today, the time is shortened even further. The uncertainty is the political will of Japanese politicians in this matter, due to the role of alliance with the U.S. and the Nuclear Non-Proliferation Treaty bindings. NPT is a comprehensive global treaty that legally forbids states from sharing nuclear weapons or aspiring to receive them, either through research or purchase.

What other options does Japan have?

In the background of this, the Japanese government is set on remilitarizing conventional weapons. The way Japanese officials speak about base-strike capabilities, which are controversial under the current constitution, Japan will soon begin acquiring them. [20] Those can theoretically include any conventional and otherwise weaponry that has the capacity to destroy an enemy military base. For these purposes, long-range rockets or bombers able to reach Chinese and North Korean territories are needed.

If nuclear sharing is introduced, we can expect Japanese politicians to probe the public support for mounting nuclear warheads on these rockets. There is also the legal issue of determining what in base-strike capabilities is still defensive and what is not. Japanese government argues that under the current constitution, Tokyo has the right to use military force at the first sign of a military operation preparation against its islands. This is an unsafe and malleable policy, as Japan will need precise military intelligence on every move inside an enemy base. Otherwise, it will be nearly impossible to determine a threshold between daily base maintenance and military action preparation against Japan. [21]

Japanese public protests against the Russian invasion and in support of Ukraine. Source: Wikimedia

Concerns and questions raised by the Japanese policy shift.

The violation of international law in Ukraine has alarmed numerous countries that border authoritarian or militaristic neighbours – the norms of peaceful coexistence are being challenged and with them, global crises come. Japan is definitely not the only one but potentially is the most important state when it comes to the questions of nuclear policy, due to the regional concentration of nuclear-armed states. Bordering two countries known for their disregard of international law, China and North Korea, every move Tokyo makes might have an adverse reaction in the aforementioned states. [22] Now it also has all the reasons to worry about Russia. Due to the volatility of the region, Japan has to be very conscious of how its actions can be perceived by its neighbours. Despite that, the Japanese government is willing to proceed with the historically largest wave of structural and normative changes towards its military. [23] It shows how tremendous the crisis is in their eyes and how little trust Japan has in its neighbours.

As mentioned above, Tokyo’s defence policy is also affected by the role of its nuclear deterrence. Japan’s identities as a victim of nuclear weapons and as a proponent of nuclear weapons are currently clashing together. If it introduces more nuclear weapons to the region, it would further aggravate China and justify North Korean anti-west propaganda in the eyes of its population. Pyongyang regime will find it easier to justify its own military build-up in the name of protecting the people from “aggressive imperialist states”, in its eyes meaning the U.S. and Japan. [24] This is only enabled as possible due to the inability of the international community to show commitment to international law. Japan’s trust in the strength of treaties is shaken due to the Russian invasion of Ukraine. Its efforts to strengthen its own nuclear capabilities suggest Tokyo’s lack of trust in the U.S. commitment to activate the nuclear umbrella if Japan becomes a target of foreign military aggression.

Japan’s current military strengthening ambitions, coupled with the general perception of insecurity from the civil society due to the events in Europe and increased North Korean hostility, could pave the way for more amendments in favour of its militarization. The constitution is supposed to prevent that. The current unprecedented military budget, positioning Japan as the third biggest military spender in the world [25], can be viewed as logical and necessary. But law amendments also follow it. If the Japanese government continues with constant, but limited law revisions over time, they could potentially mount into changes significant enough to endanger the current constitution. In turn, a lack of legal constraints could set Japan on not just a defensive, but also an openly confrontational course with its neighbours, remaking it into an imposing military power.  One with an active army that will not be called a “Self-Defence Force” anymore.

Article was reviewed by: Tomáš Zwiefelhofer, Kristýna Drmotová


  1. Belinger III, John. (2022) “How Russia’s Invasion of Ukraine Violates International Law” .org [online] Retrieved from:
  2. Gowan, Richard. (2022) “The Ukraine War and UN Reform” .org [online] Retrieved from:
  3. United Nations General Assembly, (2019) “States Not Adhering to International Obligations Undermine Rule of Law, Sixth Committee Delegates Say, as Debate on Principle Concludes”.org [online] Retrieved from:
  4. Neustaeter, Brooklyn. (2022) “What is the Budapest Memorandum and how does it impact the current crisis in Ukraine?”.ca [online] Retrieved from:
  5. Personal interviews, June 2022.
  6. United Nations News. (2022) “UN chief calls for an end to “nuclear blackmail” and risk of humanitarian Armageddon” [online] Retrieved from:
  7. Personal interviews, June 2022.
  8. Personal interviews, June 2022.
  9. Personal interviews, June 2022.
  10. Personal interviews, June 2022.
  11. (2022) “Japan protests Russian halt to World War Two peace treaty talks.” com. [online] Retrieved from:
  12. Johnson, Jesse. (2022) “Japan should consider hosting U.S. nuclear weapons, Abe says.” jp. [online] Retrieved from:
  13. Personal interviews, June 2022.
  14. Japan Today. (2022) “Kishida pledges that Japan will play leading role in diplomacy in 2023” .com [online] Retrieved from:
  15. Aoki, Naoko. (2022) “Japan may not militarize soon, but Abe’s dream lives on” .org [online] Retrieved from:
  16. Social Survey Research Center. (2022) “April 23, 2022 Public Opinion Survey Results (Free Entry).” [online] Retrieved from:
  17. Japan Anti-Nuclear Lawyers Association. (2022) “Japan Anti-Nuclear Lawyers Association 2022 General Assembly Resolution”. org [online] Retrieved from:
  18. Brumfiel, Geoff. (2004) “We have the technology” .com [online] Retrieved from:
  19. Nagayoshi, Kenji. (2022) “Why Japan’s Missile Defense Requires ‘Counterstrike Capabilities’.” [online] Retrieved from:
  20. Keita, Nakamura. (2022) “Contentious major defense policy shift shows Japan wariness of China” .com [online] Retrieved from:
  21. Ibid.
  22. Ibid.
  23. (2022) “North Korea slams Japan’s military buildup, promises action” .com [online] Retrieved from:
  24. Reynolds, Isabel. (2022) “Japan Begins Defense Upgrade With 26% Spending Increase for 2023” .com [online] Retrieved from:



Napsat komentář

Vaše e-mailová adresa nebude zveřejněna. Vyžadované informace jsou označeny *