Just so we're clear; you said North Korea got the bomb during the Obama administration. That was false.
Bush Jr. was President when North Korea got the bomb. Correct?
If you cannot acknowledge this simple fact, and admit that you were wrong, please ignore the rest of this post.
So, why didn't Bush fix it? It happened on his watch.
Obama obviously didn't *fix* it, but there were sanctions. To quote some rando on imgflip, "at least he tried".
Now, why didn't Trump fix it? Trump lifted sanctions, and got *nothing* in return.
He made things worse.