This paper is an analysis of North Korea's decision-making process regarding its Second Nuclear Test (May/2009) utilizing two choice models―Rational Choice and Cognitive Choice. The paper concludes with a suggestion for an effective/adaptive/robust deterrence strategy for the ROK-US combined forces. The Rational Choice Model (RCM), endorsed by the Expected Utility Theory,suggests that the North Korean leadership should adopt the option maximizing its expected utility in its nuclear confrontations with its opponents, while the Cognitive Choice Model (CCM), endorsed by the Prospect Theory, anticipates that Pyongyang would adopt the option meeting its reference point, heavily influenced by its domains of actions (either the domain of gains or losses). Sharing the same root and method of calculating utility, they have one explicit difference in weighting probability assigned to each outcome―the RCM weights the value and probability assigned to each outcome in a linear manner, while the CCM does so in a non-linear manner depending on the range of probability, thus resulting in a different prediction. According to the test of the hypothesis using North Korea's Second Nuclear Test (May/2009), unlike the traditional wisdom, the CCM is more explanatory than the RCM in explaining Pyongyang's strategic behavior in respect of its nuclear programs. Based on the results of this research, this essay suggests coercive strategies (mainly composed of punishment, risk, decapitation and denial strategies) exploiting the unique characteristics of air power as an alternative deterrence strategy to effectively deter North Korea in the future because it is best fitted for influencing the decision-making process of North Korea.