Realigning Priorities: The U.S.-Japan Alliance and the Future of ...

t h e I n s t i t u t e f o r F o r e i g n P o l i c y A n a ly s i s
a possible diminution in those commitments), and such
concerns, however they arise, could prompt broader consideration
of the nuclear option in Japan. The degree of
sensitivity to alliance durability is directly proportional to
the extent of perceived threats or vulnerability in Japan.
The greater the threat, the greater is the need to balance
that threat, either externally through Japan’s alliance with
the United States, or internally by means of Japanese defense
investments. For Japan to take matters into its own
hands, however, it will need to overcome significant constitutional,
political, and financial restrictions, which is
why Tokyo’s first option has always been to make more
modest investments in the alliance.
Other important factors are also worth examining in order
to determine the likelihood that Japan would seriously
consider a nuclear option, since the rationale for nuclear
weapon abstention goes somewhat beyond the two primary
reasons stated above (the absence of a sustained existential
threat and the credibility of
U.S. defense commitments). Additional
factors have been articulated
at various times in Japan,
including by secret (and apparently
influential) panels of experts,
either commissioned by,
or conducted within, the Japanese
government. 6 As a result,
a sort of conventional wisdom
has emerged on this issue with
regard to strategic, tactical, and
diplomatic reasons why possessing
or introducing nuclear
weapons is not in Japan’s national
interest.
Most Japanese defense experts,
for example, have questioned
the military utility of
nuclear weapons for such a
densely populated and geographically small country as
Japan (Kase 2001 and interview 2007a). 7 This is true even
though France and the United Kingdom, also relatively
small states, deployed nuclear forces several decades
ago and have continued to modernize their capabilities.
Whatever its validity against a larger nuclear power such
as China or Russia, this point about a lack of strategic
6 The first known report was written by
four nongovernmental Japanese university
academics specializing in international
security and nuclear science, and
commissioned by Prime Minister Sato
in the late 1960s (often referred to as the
1968/70 report, since it was completed in
two stages; see Kase 2001). Then, JDA director
general Nakasone Yasuhiro ordered
a separate cost/benefit study in 1970. The
third report was an internal JDA assessment
in 1994/95 of nuclear threats and
deterrence strategies following the end
of the Cold War (see Hughes 2007). Other
related studies are likely to have been
carried out at various levels of formality,
including one reportedly completed
in September 2006 (Tamura 2006).
7 There are exceptions, of course,
throughout postwar Japanese history. A
good example is former Maritime Self-Defense
Forces (MSDF) chief of staff Uchida
Kazuomi, who believed in the late 1960s
and early 1970s that “nuclear weapons
were absolutely necessary for the defense
of Japan,” particularly to counter Soviet
submarines (Mainichi Daily News 1994b).
depth is less applicable if Japan’s goal is to deter a smaller
country such as North Korea, since North Korea would
certainly be vulnerable to nuclear retaliation from Japan.
Moreover, the deterrence equation shifts somewhat in Japan’s
favor if the MD systems it is deploying prove effective
at destroying incoming missiles.
There are signs that at least a few Self-Defense Force
(SDF) officers are sympathetic to these kinds of arguments.
In an article penned anonymously by a “voluntary
study group” of SDF officers in their early forties, for example,
the authors write, “When we insist that Japan needs
a nuclear weapon, we always hear negative opinions such
as ‘Japan does not have an appropriate nuclear test site,’
or ‘Japan does not have a place to deploy a nuclear missile.’
However, these are such small issues…Israel has been
nuclear-armed even though it has only a small territory, as
large as Shikoku island in Japan. Today’s Japan is a much
more vulnerable state than Israel because Japan is circled
by nuclear armed states such as China, Russia and North
Korea” (Group Ichigaya 2007). Still, most Japanese specialists
agree with a leading defense analyst who dismissed
this kind of argument, “There are those who get excited
about the idea of discussing a nuclear option…but it is an
emotional argument, not strategic” (interview 2007g).
Some prominent Japanese foreign policy specialists,
however, do suggest that even if it was not sufficient to deter
a China-scale force in all circumstances, a Japanese national
nuclear deterrent could so complicate strategic calculations
in Beijing that China would think twice before
threatening to use (or actually use) its own nuclear forces
in a regional crisis or conflict (Okazaki 2003). In this way,
so the argument goes, Japan could play a reinforcing role
to the U.S. strategic deterrent, as the British nuclear force
to some extent has done in Europe (Group Ichigaya 2007).
Strategic calculations are beginning to find their way into
the debate.
Another argument against the nuclear option advanced
in Japan was the fear that a nuclear Japan could
spark a regional arms race. “[Japan’s deployment of nuclear
weapons] would significantly destabilize East Asia,
which in turn would possibly threaten Japan’s security …
[so] a nuclear arms race is an unfavorable game for Japan”
(Kitaoka 2006). Such a move would also likely undermine
Japan’s efforts to obtain a permanent seat on the UN Security
Council and strengthen the NPT and global non-
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The U.S.-Japan Alliance and the Future of Extended Deterrence