Relations between the two Koreas continue to be hostile, volatile and unpredictable with North Korea’s nuclear issue remaining as untamed as ever. As such, there is a growing urgency for security cooperation in Northeast Asia to be given immediate attention. The key players in the region - the US, China, Japan and Russia - are keenly aware of the security threat of an armed clash between North and South Korea and are committed to denuclearization of the Korean peninsula. This book explores the domestic factors of the two Koreas and the four major powers that influence their security policies towards North Korea and Northeast Asia. This well thought out and consistently analysed volume has huge potential to frame the conversation on Northeast Asian relations in the coming years.