Of course, Donald Trump flunked the Hanoi negotiations. But, let's not forget, he is no master diplomat, and for him to back down, despite his desperate need for any kind a victory, is quite commendable. 

Moreover, it's way more complicated than your average negotiations. The North Korean dilemma had been simmering on the backburner for over quarter a century (three Presidents already).

Source: https://www.nytimes.com/…/asia/trump-kim-jong-un-summit.html