It has always seemed incredible that a poor country like North Korea could develop not just one but three kinds of nuclear weapons—those fueled by plutonium, those fueled by uranium, and (according to North Korean claims) those fueled by hydrogen—plus the missiles to deliver them. Such disbelief may be the reason why, as Panda points out, the West did little to stop the process until it was too late. His deeply informed book explains as much as is publicly known about how Pyongyang developed nuclear weapons. The government reverse engineered missiles from China and the Soviet Union, got uranium-enrichment centrifuges from the Pakistani official A. Q. Khan in exchange for missile technology, and hired Russian engineers after the collapse of the Soviet Union. But most of the work was done by the country’s own scientists, about whom little is known. Today, North Korean bombs threaten not only U.S. bases in Guam, Japan, and South Korea but the whole American mainland. If there is any good news, it is that Panda believes Pyongyang does not intend to use these weapons for aggression—at least not yet—only to disrupt a planned U.S. invasion before it can happen. The bad news is that Pyongyang might interpret almost any action taken by U.S. forces as just such preparation for an invasion.