It appears that the only country that has any influence on North Korea is China. China's military says that they are conducting unrestricted warfare against the US, so it is unlikely that they will help us with North Korea. We are currently selling air defense missiles to Japan, but I think we have not agreed to sell them to Taiwan. I wonder what China's reaction would be if we said that if North Korea's nuclear missile programs are not stopped we will sell both air defense missiles and offensive missiles with nuclear warheads to both Japan and Tiawan. That might get China's attention and give them some incentive to help kill the North Korean weapons programs. It would probably get some reaction from South Korea, which also hasn't been helping us much.