Japanese defense analysts believe North Korea is ready to test it's Taepodong 2 missile later this year. This missile might have a range of up to 6,000 kilometers, enabling it to reach the west coast of the United States. In 1998, North Korea scared the Japanese when they test fired a Taepodong 1 missile by firing it over Japan and into the Pacific ocean. The Taepodong 1  has a range of 2500 kilometers and appears to have a fairly primitive guidance system. With an improved guidance system, the Taepodong 2 could probably hit a major metropolitan area, like Seattle, with a nuclear weapon. However, engineering such a guidance system, and the electronic systems needed to achieve an successful nuclear detonation at the other end, is difficult. So far, North Korea has not even tested  a nuclear weapon, so they are not sure their nuclear weapon design will work, and to what extent.