April 3, 2004 TOKYO, April 2 — As the United States races to erect a ballistic missile defense system by the end of the year, it is quietly enlisting Japan and other allies in Asia to take part in the network, which could reshape the balance of power in the region. Last week, a few days after the United States Navy announced that it would deploy a destroyer in September in the Sea of Japan as a first step in forming a system capable of intercepting missiles, Japan's Parliament approved spending $1 billion this year to start work on a...