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
themselves, and keeping track of these and other developments
should help Washington to maintain effective extended
deterrence.
An often overlooked area of the extended deterrence issue
is Japan’s own technical capacity to produce a nuclear
deterrent, if it decided that such a paradigm shift was necessary.
After all, the domestic
legal and political barriers to
nuclear weapons development
(or introduction) will be
the last to fall if Japan ever decided
on such a course. If policy
makers grew more nervous about the future and wanted
to shorten the lead time to developing strategic nuclear
options of their own, they could initiate interim steps under
the radar that seek to enhance Japan’s domestic industrial
and scientific capacity in this area. Though many
of these steps would be extremely difficult for outsiders
to recognize, some of them might be visible, and together
with other telltale signs of more active hedging by Japanese
policy makers, Washington can better evaluate what
its ally thinks about the future of the alliance and how to
keep it serving both countries’ interests.
49 See, for example, Federation of American
Scientists 2000 and Kamiya 2002, respectively.
50 The U.S. Department of Energy’s guidance
on the issue of using reactor-grade plutonium
in nuclear weapons suggests that an advanced
NWS using modern designs could produce reliable
weapons comparable to those produced
using weapons-grade plutonium (Miller 2002).
Technical and scientific capacity
If the regional security equation tilts further out of Japan’s
favor, either because of a demonstrated North Korean
capacity to deliver nuclear weapons on Japan or the U.S.
mainland, Chinese deployment of aircraft carriers, or some
similar development, Japanese policy makers are likely to
respond by taking incremental steps toward enhancing external
and internal balancing. If the potential for external
balancing seems insufficient or in doubt for some reason,
then internal balancing will take on more importance. Policies
to support internal balancing will be relatively quiet
and unobtrusive at first, but they will become increasingly
obvious if the situation worsens.
Some change is already noticeable in the area of defense-related
science and technology R&D, but many formal
and informal barriers still exist between the research
and defense communities in Japan that retard the application
of new technologies for national security purposes, especially
anything related to nuclear weapons or offensive
strike systems. But if U.S. policy makers are going to notice
these incremental changes in defense industrial and
scientific policies, especially in the nuclear area, they first
need to establish some sort of baseline regarding Japan’s
current technical readiness to build a nuclear bomb.
Past studies of Japan’s nuclear options are remarkable
in their lack of consensus about seemingly concrete details
on this point, with some concluding that Japan is technically
capable of developing a nuclear weapon within a year
(some even suggest six months or less), while others argue
that it would take at least a decade. 49 As early as 1966, a
then-classified U.S. national intelligence estimate concluded
that it would take about two years for Japan to produce
and test a nuclear weapon, if it could get uranium without
safeguards (National Security Archive 2005). One wonders
what the official U.S. estimate might be today.
A respected Japanese professor of nuclear engineering
told a Japanese newspaper that “it takes at least a year to
develop a nuclear bomb, going through the whole process
from design, manufacture and verification to a detonation
test,” but “several years” if the time needed to build a nuclear
reactor ( for producing the ideal fuel) and related facilities
are included (Daily Yomiuri 2007). As noted earlier,
the Sankei Shimbun reported on a secret government-requested
study in 2006 that estimated it would take “at
least 3 to 5 years until Japan can go into trial production
of a miniaturized warhead” (Tamura 2006).
Most of these estimates account for the ancillary infrastructure
necessary to build a viable nuclear weapons
program (such as a reliable delivery system or command
and control), but they are still artificial because they do
not account for the domestic legal and political obstacles
that must be overcome. Even with such caveats, however,
we have found nothing to suggest that Japan could develop
a safe and functioning nuclear deterrent in less than
one year, but within two years is another story.
Those who claim that Japan could build a nuclear arsenal
relatively easily point first to the country’s large civilian
nuclear energy program, the self-contained nature
of its nuclear fuel cycle (including uranium enrichment
and fuel reprocessing capability), and its growing stockpile
of plutonium (over 40 tons). Even though Japan’s stock of
plutonium is reactor grade, which is less easily converted
for use in nuclear weapons, it nonetheless can be used for
weapons, and this would provide Japan with the raw materials
for hundreds of nuclear warheads. 50 Japan’s newest
nuclear reprocessing plant (Rokkasho) produced its first
test batch of fuel (a uranium-plutonium mixture known as
44
The U.S.-Japan Alliance and the Future of Extended Deterrence