North Korea’s launch of a new missile has set off alarm in Japan. The alarm is warranted insofar as the new missile, called the Taepodong I by U.S. intelligence, is capable of reaching Japan. Yet the launch was more likely an unsuccessful attempt to mark Kim Jong Il’s formal accession to power by boosting a small satellite into space than a brazen act of intimidation. Overreaction to the test will impede diplomacy, which is the most promising way to curb Pyongyang’s missile program.