Unless China has an unlikely change of heart regarding cutting off oil, food & other trade until NK halts its atomic weapon / missile programs, the world will have to live with NK as a nuclear power.

Alternatively, military options might succeed in the long run, but not without, at the least, the destruction of Seoul SK and 20-30million casualties and U S participation in another "Police Action" ( aka: War) on the Korean Peninsula. Baaad Idea! Military decapitation/ counter force ops might even end up in a general war.

Soooooo...... ( I cannot believe I'm about to say this), the best prep may be to quietly tell China that failing NK freezing said programs, we are going to GIVE SK and Japan their own atomic weapons, to insure a type of MAD ( mutually assuered destruction), hot peace. The conversation would include a hard date on which we would commence our atomic gift.

This would be a quiet announcement, initially privately delivered, perhaps a secret Tillerson trip to China, a la Kissinger. It would not be a Twitter tirade or a beilicose public threat.

Even if that threat doesn't work at halting NK, MAD has worked for almost 70 years. China and Korea fear Japan, with good historical reasons. China might even fear the possibility of a nuclear armed Japan/SK, enough to take some real actions to control NK. If not, MAD should still work. Anything is better than the U S getting into another land war in Asia

Sometimes smart prepping includes an asymmetrical collective national defense.