Mr. Rumsfeld's warning is striking because the unexpected 1941 attack on the most important U.S. Pacific base was a huge military catastrophe. The nearest existing international rule is the concept of the high seas and everybody's right to use them without interfering with others. It is not too late to shift thinking about space from its being the next battlefield to being a global common that all have an interest in keeping peaceful. But that cannot be taken for granted while at the same time one is planning for military encounters. There must be an open, searching debate on the technology and politics of missile defense and also on how the United States views space, if the world is not to drift into another threat of cataclysmic confrontation.
Unintended consequences can become unavoidable.