NK is able to get away with the chest thumping because their neighbors to the north are reluctant to step in, even though China has stated often enough that they didn't like the threats coming from NK. Until China poses a real threat to NK, Un is going to keep mouthing off. He's been flippant to us because of distance. With todays surveillance anyone from anywhere can see whatever is going on. However, with as much military might as China has and with as quickly as they can move it in, NK isn't going to fuck with a viable threat from them.