I just came across this very engaging op/ed at The Japan Times [edited for length and highlighted for my emphasis]:
Collective self-defense and collective security: what the differences mean for Japan
By CRAIG MARTIN
Thursday, Aug. 30, 2007
PHILADELPHIA – As the debate in Japan heats up over whether and how to amend Article 9 of the Constitution, the terms “collective self-defense” and “collective security” are often used in the same breath, almost as though they were synonymous. Often the terms are avoided altogether.
The terms “collective self-defense” and “collective security,” however, each have a very precise meaning under international law, and the amendment of Article 9 to allow Japan to engage in either one would have very specific and different consequences. […] A more precise use of these terms ought to preclude the government from hiding behind such woolly terms as “international peace cooperation activities.”
Collective self-defense is authorized, along with individual self-defense, by Article 51 of the United Nations Charter. Put simply, if a country in the international system has suffered an armed attack, then any other country has the right, but not the duty, to use armed force against the aggressor in reliance upon the principle of collective self-defense.
The only preconditions, in addition to the determination that an armed attack has occurred or is irrevocably in motion, are that the use of force is deemed necessary, that the force is proportionate to that used in the attack or the threat posed, and that it is immediate.
What is crucial to recognize here, however, is that there is no requirement that the U.N. Security Council make any prior determinations, much less authorize the use of force.
In contrast, collective security involves the use of force to maintain or restore international peace and security, as authorized by the U.N. Security Council under Chapter VII, and specifically Article 42, of the U.N. Charter. There need be no “armed attack” as a conditional precedent, but merely a determination by the Security Council that there is a threat to the peace, a breach of the peace, or an act of aggression, such that the use of force or other measures are required to maintain or restore international peace and security.
So the scope of collective security operations is much broader and the threshold for its use much lower, than for collective self-defense; but states may not act unilaterally, singly or together, under the guise of collective security. Authorization by the U.N. Security Council is necessary.
It should be clear, therefore, that any amendment of Article 9 to explicitly authorize Japan to exercise a right of collective self-defense, would be to thereby give the government the power to use force anywhere in the world upon its own determination that there had been an armed attack against another state. Given the U.S.-Japan Security Treaty, Japan could be called upon to defend the U.S. anywhere in the world.
The government of Japan has tried to narrow the discussion of collective self-defense to specific examples, such as the interception of ballistic missiles targeting the U.S. It has thus created the mistaken illusion that somehow collective self-defense can be limited to such narrow circumstances. But once the Constitution is amended to permit collective self-defense, the government will be free to use force on the other side of the world so long as the conditions for collective self-defense are satisfied.
The fundamental question, therefore, is whether the Constitution should be amended to allow collective self-defense, or collective security, or both. The fact that the LDP draft constitutional amendment proposal uses highly ambiguous language that could encompass both concepts is problematic, and should be viewed with suspicion.
Ichiro Ozawa, leader of the Democratic Party of Japan, has argued that Japan may have some obligation to participate in the U.N. collective security system. Japan joined the U.N. and became a party to the U.N. Charter, and so arguably accepted an obligation to participate in its collective security system.
Japan might, therefore, seriously consider providing constitutional authority for collective security operations, together with carefully crafted oversight and approval requirements, in any amendment to Article 9. That would not be inconsistent with the spirit of the preamble of the Japanese Constitution.
But that is a far cry from authorizing collective self-defense. There is no duty under international law to engage in collective self-defense, nor is it consistent with the spirit of the renunciation of war and the use of force for purposes of resolving international disputes that is articulated in Article 9. Nor is it clear that it would be in the long-term interests of Japan, given the likely response of neighboring countries to such a policy shift.
In any event, however, any amendment to Article 9 ought to be very clear as to precisely what purposes armed force may be used for, and under what conditions. Such ambiguous terms as “international peace cooperation activity” ought to be banished from the debate, and from explanations of government defense policy.