This introduction presents an overview of key concepts discussed in the subsequent chapters of this book. The book presents in-depth analyses of the inter-Korean and international dynamics of North Korea's second nuclear crisis, provide new insights into the on-going six-party talks, and offer some creative formulas to resolve the nuclear crisis through peaceful, diplomatic means. It describes how the second North Korean nuclear crisis begins, evolved and the nuclear issue affected inter-Korean reconciliation and vice versa, what are the interests and policies of the major powers at the six-party negotiating table. The book explores the short-term and long-term implications of North Korea's nuclear blast and how should the two Koreas and the surround powers untangle North Korea's nuclear knot for a lasting peace and security in and around the Korean peninsula. It also describes United States (US) President Bush's approved deal with North Korea signed by Christopher Hill in Berlin, which led to the February 13 nuclear agreement in Beijing.