Japan has decided to use its missile defense system
solely to intercept ballistic missiles targeting Japan,
not missiles that pass over Japan and target other
countries including the United States, government
sources said Saturday.
The government has decided to limit the scope of
interception by the missile defense system, to be
deployed in fiscal 2007, because intercepting missiles
that are targeted at other countries would be construed
as collective self-defense.
According to the Japanese government's interpretation,
under international law Japan has the right to
collective self-defense -- which is the right to use
force to counter a foreign attack on an allied country
-- but Japan's war-renouncing Constitution forbids the
exercise of that right.
The government will explain the decision during Diet
deliberations if it submits legislation on missile
defense to the upcoming ordinary session, the sources
Political analysts say, however, that Japan will likely
be hard-pressed by the United States, which is expected
to show discontent over the decision as it would bar
Japan from taking any action against missiles aimed at
the United States that pass over Japanese territory.
The target of a ballistic missile can be predicted by
its speed and angle as it leaves the atmosphere.
A missile fired by North Korea, for example, will not
pass over Japan if it is targeted at the U.S. mainland,
but if it is targeted at Hawaii and Guam it will pass
through Japanese skies.
The government had once judged it possible to shoot down
missiles that travel over Japan by interpreting such an
action as exercising its right to individual
self-defense given the possibility that some missile
parts could fall on Japanese territory.
But it finally determined that intercepting missiles not
targeting Japan would pose a constitutional problem, the
A gray zone remains, however, as the government had said
in past Diet sessions that in cases where the precise
destination of a missile cannot be predicted, it will
consider the probability of it targeting Japan as high
and such a launch as an armed attack against Japan,
Senior officials of Japan's Defense Agency also said
interception would be inevitable in cases where Japan
cannot specify where the ballistic missile will land.
Japan has recently decided to purchase a missile
interception system from the United States, apparently
to deal with possible ballistic missile attacks from
Under the system, Japan would intercept an incoming
ballistic missile outside the atmosphere, using an SM-3
standard missile carried on destroyers equipped with the
Aegis air defense system.
If the SM-3 fails to shoot it down, a ground-based PAC-3
missile will try to intercept it before it reaches its