He fell in love. Remember? And he said he would have denuclearization? Right? The former may have happened but the latter did not. He has continued to make claims to the contrary, that his approach worked and yielded results. Comprehensively, nothing can be shown to evidence any success whatsoever.
Comprehensively, nothing can be shown to evidence any failure whatsoever either.
Of course neither of us can make any claims of what a second Trump admin would have accomplished...
But I think the general knowledge in the US that Beiging directs any offense by NK is very useful.