Military empires are always arrogant. Assign to themselves infallible righteousness, infinite power, highest hypocrisy. The U.S., claimed to be the biggest, the best and the mightiest military and economic power ever existed in the history of man, have been accustomed to setting the rules for the world. But  exempt them from itself. Exceptionalism indeed. 

The only power who nuked an enemy into defeat give itself the power to say what sovereign states can have nuclear weapons, can have this or that missiles, can use force on whatever. Itself exempted. Would Mattis allow Japan to have nuclear weapons? Pakistan got nuke. Why don't Mattis go and nuke them? 

Do China and Russia, direct neighbors, feel threatened by NK nukes? Hardly a word from them. So peaceful. Why does the Pentagon feel so threatened? Simple: it killed 3 million North Koreans and revenge is in the card. 

In a few years Mattis will be gone from office. NK revenge will be around for another century.