The U.S. Department of Defense says that North Korea has increased the accuracy of the guidance systems in its long range missiles. While North Korea has not flight tested any missiles since 1999, it has apparently received technology from foreign nations. The Department of Defense would not reveal the source of this new information, in order to protect sources. North Korea has, for decades, obtained military technology any way it could. In the past decade, most of this technology has been stolen, often using foreigners who have illegally diverted militarily useful technology to North Korea.