There is no military solution to North Korea. In every war-games exercise ever, South Korea loses a city. This is coming also when the US usually over estimates its own ability. Capitalism is the best weapon. The People in North Korea are starving. Lift sanctions on agriculture products and end the collective punishment.
Try the carrot instead of the stick. North Korea is not going to weaponize food. Return to the 6 member talks where China North Korea South Korea and Russia all agreed on a solution that unfortunately the US and Japan rejected. Allow inspectors in and dismantle the nuclear program in steps in return for rewards at each step.