Extended Deterrence in the Japan-U.S. Alliance

NAPSNet Special Report

Recommended Citation

Ken Jimbo, "Extended Deterrence in the Japan-U.S. Alliance", NAPSNet Special Reports, May 08, 2012, https://nautilus.org/napsnet/napsnet-special-reports/extended-deterrence-in-the-japan-u-s-alliance/

by Ken Jimbo

May 8th 2012

This report was originally presented at the East Asia Nuclear Security workshop held on November 11, 2011 in Tokyo, Japan. All of the papers and presentations given at the workshop are available here, along with the full agenda, participant list and a workshop photo gallery.

Nautilus invites your contributions to this forum, including any responses to this report.


I. Introduction

II. Report by Ken Jimbo

III. References

IV. Nautilus invites your responses

I. Introduction

In the following report Ken Jimbo assesses the impacts of U.S. extended nuclear deterrence in Asia–especially on the Korean peninsula and in China–and how it relates to Japan’s “dynamic defense” policy adopted in the 2010 National Defense Program Guidelines. He states that “[s]ince the strategic landscape in Northeast Asia is increasingly complex in character, it is difficult to apply the concept of deterrence in a “one-size-fits-all” manner.  For extended deterrence to succeed, the Japan-U.S. alliance needs continuous updates on the assessment of the distribution of powers and threats, then to apply tailored deterrence to the regional dynamic.”

Ken Jimbo is an Associate Professor at Keio University, Japan.

The views expressed in this report do not necessarily reflect the official policy or position of the Nautilus Institute. Readers should note that Nautilus seeks a diversity of views and opinions on significant topics in order to identify common ground.

II. Report by Ken Jimbo

-“Extended Deterrence in the Japan-U.S. Alliance”

During the process of drafting the Nuclear Posture Review (NPR 2010), extended deterrence was one of the most important imperatives of prescribing U.S. nuclear doctrines, force postures and readiness.  In spite of its importance, there has been wide-ranging disagreement among U.S. policy makers and scholars about what constitutes effective extended deterrence and the role nuclear weapons play.  In Japan silent but vigorous debate on nuclear extended deterrence has taken place since President Obama’s Prague speech and during the process of releasing the Quadrennial Defense Review (QDR), the Ballistic Missile Defense Review (BMDR) and NPR.

Extended deterrence, in the most simplified terms, is extending deterrence to third parties.  Extended deterrence, however, is harder to achieve than central (or individual) deterrence because: 1) it needs to be a threat credible to an adversary on behalf of or in collaboration with the deterrence provider, 2) it needs to convince the elites of both the guarantor and guarantee states on a bipartisan basis that it is credible 3) it needs to assure the domestic public that such forms of extended deterrence are necessary. Essentially, extended deterrence is the sets of multi-dimensional perceptions of the credibility of U.S. security commitments to its allies.

Since the strategic landscape in Northeast Asia is increasingly complex in character, it is difficult to apply the concept of deterrence in a “one-size-fits-all” manner.  For extended deterrence to succeed, the Japan-U.S. alliance needs continuous updates on the assessment of the distribution of powers and threats, then to apply tailored deterrence to the regional dynamic.

Asian Dimension of Extended Deterrence

North Korea

In an Asian dimension, extended deterrence is particularly important for two reasons.  First, it’s major function is to deter and dissuade any large-scale aggression on the part of  North Korea.

The failure to denuclearize North Korea has left Japan facing the DPRK’s increased nuclear and missile capabilities.  In 2010, North Korea increased its level of aggression by sinking the South Korean corvette Cheonan and shelling Yonpyong Island.  These events draw huge lessons for the effectiveness of extended deterrence. North Korea may expand its aggression to a degree that may not invite a major retaliation from the ROK or the United States.  With its increased confidence, North Korea might have calculated that the extent to which it can provoke the ROK or possibly Japan, has gone up.

We may tentatively conclude that the “stability-instability paradox” is likely to come into play here.  There is a decreasing probability of a major war, but an increasing probability of low-level conflicts.  North Korea assumes that South Korea and the US do not want minor conflicts to escalate into major ones, making it safe to engage in the former.

North Korea was careful enough to strike a ‘disputed’ area, one which was—at least from their point of view—not a part of the territory covered by the US umbrella. In doing so, it may have acted like Egypt and Syria did in 1973: facing a nuclear-armed adversary, they were very careful not to attack Israel on its 1948 borders.  South Korea retaliated in response to the Yeonpyeong shelling by firing about 80 shells at North Korean barracks, command structures and artillery near the border, but there was no further significant military escalation from North Korea despite its verbal attacks.  South Korean F-16 and F-15 jets were also rushed to the area, but they did not provoke North Korean targets. More importantly, the US did not directly take joint action during the initial counter strikes. In terms of the possible range of escalation, the offensive exchanges in the Yeonpyeong case were relatively low in intensity. We can tentatively observe that deterrence failed in the latter part of 2010, and it may fail again, but that escalation control succeeded.

The lesson we learned from 2010 was that the US and ROK have to carefully review how to respond to small-to-medium scale aggression by reconfiguring the deterrence structure vis-à-vis North Korea.  In order to deal with China’s probing behavior in East China Sea, Japan adopted a concept called “Dynamic Defense” or “Dynamic Deterrence” in the National Defense Program Guideline 2010 which emphasized the operational domain of the Self Defense Force by demonstrating upgraded intelligence, surveillance, and reconnaissance activities to close the windows of opportunity for China to expand its activities surrounding Japan [1].

Northeast Asia is also faced with the fragile and abrupt generational transition taking place in North Korea, which has increased the uncertainty of the regime’s stability.  If some internally destabilizing or hard-landing scenario should happen, certainly the U.S. forward presence will undertake a stabilization operation in the North, and during such a scenario extended deterrence plays a key role to ensure the stability during the crisis and to limit damage as a result of possible attacks from North Korea.


The second important aspect of extended deterrence in the Asian context is China. This is another complex question since China has not only modernized their nuclear arsenals, but also significantly increased the capability of their conventional forces.  Growing Chinese anti-access and area-denial capabilities would impede the deployment of U.S. forces into the combat theater and limit the locations from which those forces could effectively operate.  These aspects have certainly increased the cost and complexity of U.S. military responses to crises in East Asia.

When it comes to the Sino-Japanese bilateral dimensions of the regional balance of power, China already has twice the defense budget than Japan (according to SIPRI standards), and it is going to be four to six times larger in 2020, and seven to ten times larger in 2030—although these figures are based on optimistic Chinese economic projections for the next two decades.  We are now seeing a dynamic wherin China increasingly has denial power against the United States, whereas Japan’s relative power decline has become more apparent. Crafting extended deterrence under this new dynamic is one of the most important challenges of managing the alliance in coming years.

In the Nuclear Posture Review, the term given to China’s position is “ensuring strategic stability”.  We need to be constantly updating this concept.  What if they deploy highly modernized strategic forces such as land based DF-31A, tactical DF-21 and submarine based JL-2?  It is a matter of time until China becomes more confident in gaining credible second-strike capability against the United States and its allies.  Then the question arises: how do we define nuclear relations between the U.S. and China?

Tailored Regional Deterrence Architecture

The QDR, NPR and BMDR emphasize the importance of crafting “Tailored Regional Deterrence Architecture”.

This unique DOD approach to the deterrence concept suggest that deterrence has to be adjusted to the uniqueness of the region, and the components of deterrence include various forms ranging from nuclear to non-nuclear striking forces, missile defense and counter-WMD capabilities. The underlying goal of these reviews is to de-emphasize the role of nuclear weapons.  Accordingly, non-nuclear elements will have to play a vital role for enhancing extended-deterrence.

As a result, the NPR declared the retirement of the TLAM/N, nuclear tomahawk that has been in storage since the Navy completed the withdrawal in early 1990s.  Indeed, there was a certain amount of concern in the Japanese policy community that the retirement symbolizes the reducing visibility of U.S. nuclear commitments in Asia.  But as stated in the NPR, TLAM/N was one of a number of means to forward-deploy nuclear weapons in the crisis.  The role of TLAM/N can be substituted by heavy bombers/dual-capable fighters/ICBMs and SLBMs.  I think that ensuring the visibility of the U.S. nuclear commitment in Asia by flexibly forward deploying the air-component will become highly important in post-NPR extended deterrence in Asia.

Non-First Use and the “Sole-Purpose” Debate

Japan highly appreciates that the NPR did not adopt a universal policy that “sole purpose” of U.S. nuclear weapons is to deter nuclear attack on the U.S. and its allies.  Given North Korea’s potential capability to attack Japan with chemical and biological weapons, it is still crucial for Japan that the U.S. reserved the right to use nuclear weapons in response to a CBW attack. Even though there is much debate that conventional forces can replace the role of nuclear weapons both in peace-time and during crisis, I think that nuclear extended deterrence still plays a crucial role for simplifying Pyongyang’s calculations over their strategic value of possessing nuclear, biological and chemical weapons.

NDPG 2010 and Extended Deterrence: Towards Flexible Response

The 2010 NDPG states:

as long as nuclear weapons exist, the extended deterrence provided by the United States, with nuclear deterrent as a vital element, will be indispensable. In order to maintain and improve the credibility of the extended deterrence, Japan will closely cooperate with the United States, and will also appropriately implement its own efforts, including ballistic missile defense and civil protection.”

It is significant that Japan recognizes the U.S. nuclear deterrent as vital and extended deterrence as indispensable.  At the same time, the introduction of Japan’s “dynamic defense” concept will promote the role of JSDF to play a more active role in deterrence, especially with respect to those North Korean and Chinese activities on fait accompli and proving.  U.S. extended deterrence will continue to play a significant role in peacetime deterrence and escalation management.  It will be imperative for Japan and U.S. to activate the seamless deterrence capability from low-intensity to mid/high intensity response with merging “dynamic defense” and extended deterrence.

III. References

[1] “Dynamic Defense” in the New Guidelines places importance especially the principle of the Self-Defense Forces’ “activities.” Particularly on to 1) strengthen preparation against military activities of neighboring countries through reinforcing regular intelligence, surveillance, and reconnaissance activities which called as “ISR,” 2) quickly and seamlessly respond to various contingencies, and 3) multi-layered promotion of cooperative activities with foreign countries.

IV. Nautilus invites your responses

The Nautilus Peace and Security Network invites your responses to this report. Please send responses to: napsnet@nautilus.org. Responses will be considered for redistribution to the network only if they include the author’s name, affiliation, and explicit consent.