This talk will focus on the technical aspects of the THAAD missile defense system that are relevant to the domestic and foreign policy debates in South Korea and the United States over the deployment of this missile defense. It will be shown that the THAAD missile defense will be very susceptible to simple countermeasures that are well within the technical capacity of North Korea to implement. This extreme vulnerability to countermeasures is due to the THAAD design, which was conceived from the beginning for a high-altitude intercept capability that uses infrared homing. The countermeasures that will be described would not only be effective against THAAD, but they could be implemented by North Korea with essentially no loss in the existing anti-military and damage inflicting capacities of its current rocket forces. The talk will also explain why a THAAD radar in South Korea has caused concern in China.