First of two parts
As tensions mount over the planned launch of a North Korean rocket, so too are doubts about the effectiveness of Japan's ballistic missile shield, which has never been used in a real-world situation.
The communist state announced plans last month to send a Kwangmyongsong-2 communications satellite into space sometime between April 4 and 8. The United States and South Korea, however, have accused the North of using the launch as an excuse to test an intercontinental ballistic missile.