For North Korea, a nuclear weapons program is no longer a distant goal but a present reality . After years spent developing viable nuclear and missiles programs , Pyongyang is unlikely to trade them away in negotiations any time soon. Instead it will continue to cultivate its nuclear capabilities , seeking security through a credible nuclear deterrent. At the same time, regional and global powers are working to adapt their military strategies to accommodate North Korea's newfound nuclear abilities. The issue is driving anti-ballistic missile defense development, reinforcing the U.S. military's rebalance toward the Pacific and causing Japan to reconsider weapons systems it previously eschewed . Perhaps most important, North Korea's investment in nuclear weaponry has prompted South Korea to adopt an increasingly pre-emptive and aggressive force posture and policy, fostering an atmosphere of instability on the Korean Peninsula and raising the likelihood of conflict. An Evolving Deterrence Strategy .