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 2007 Defense White Paper uses only the ambiguous and legally meaningless term "international peace cooperation activities."

Similarly, the Liberal Democratic Party's constitutional amendment proposal provides in its draft Article 9 that "the Self-Defense Military may engage in international cooperative activity to ensure the peace and security of the international society." That could include both concepts.

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. It is important, therefore, that when these terms are used in this debate, everyone understands what exactly is meant and what would be the ramifications of permitting either one. Moreover, a more precise use of these terms ought to preclude the government from hiding behind such woolly terms as "international peace cooperation activities."