Where does Donald Trump go from here on North Korea?

By every measure, Hanoi has been an embarrassment for the US president, writes The National's Chief Diplomatic Correspondent

People read about the Kim Jong-un-Donald Trump meeting in the North Korean Rodong Sinmun newspaper in a square in Pyongyang. AFP

If Donald Trump thought Kim Jong-un was going to be taken in by a charm offensive, he now knows differently.

The work of diplomacy is often dull and painstaking. Language matters. Details count. When it comes to dismantling the labyrinthine infrastructure required to become a nuclear-armed state, you cannot wing it.

Unfortunately, Mr Trump's transparent shtick has fallen a long way short of the due diligence that any disarmament deal would require. While he did walk away on his own terms, he did so at a cost. His opponent did not blink or yield to overtures that lacked substance. If anything, Mr Kim, who leads a communist regime that abuses its citizens, presides over food poverty and has shown willingness to threaten its neighbours with nuclear annihilation, emerges stronger.

Mr Trump should now realise that the North Korean leader is not a nice guy. The pair's supposed chemistry is not a substitute for deeds. It will take more than the unsubstantiated promise of an economic transformation to persuade North Korea to give up nuclear weapons. The estimate of Mr Trump's intelligence agencies – that Pyongyang has done nothing to reverse its atomic activities – is starkly at odds with the proselytising rhetoric that the president has reserved for Mr Kim.

This disconnect, eight months after a promising if sketchy start to nuclear talks in Singapore, shows the current lack of an enforceable US strategy to bring about the North's denuclearisation.

Mr Trump's preferred messaging device is limited to 280 characters or less. It is there, on Twitter and in public, that he has routinely pilloried Barack Obama's administration for the nuclear deal it did with Iran, and other world powers. It took years of painstaking face-to-face talks between those countries to persuade Iran to rein in its atomic programme. Unlike North Korea, Iran does not and has never possessed nuclear weapons.

The biggest risk following Hanoi is that Mr Kim can use the diplomacy spearheaded by Mr Trump to buy himself more time. The talks in the Vietnamese capital took place against the incongruous background of Mr Trump's former lawyer Michael Cohen's testimony to Congress about the US president. In many ways, the unseemly details overshadowed Mr Trump's talks with Mr Kim, which never really got off the ground.

The North Korean leader may well be wondering how long Mr Trump will be in the White House. Why should he do a deal? Does he really need to? His answers will emerge soon enough as he and his team in Pyongyang will digest the past two days and plan their next move. Mr Trump should do the same because he left Vietnam without anything to back up his big talk. He faces an adversary, not a friend, and when it comes to diplomacy he has been made to look like an amateur whose words have so far proven the adage that talk is cheap.