Hanoi summit: Trump walks but time is on Kim Jong Un's side

Who won and who lost the second round of negotiations between North Korea and the United States, which ended abruptly and without agreementin Hanoi on Thursday?

It sounds like a glib question when the fate of millions is at stake, but it is also a revealing way to examine what happened and where things may go from here.

North Korea has done well.

In 2017 it was a diplomatically isolated pariah state subject to lurid threats from President Trump: "North Korea best not make any more threats to the United States ... They will be met with fire and fury like the world has never seen".

Now its leader is sharing the world stage with him. Images of Kim Jong Un alongside Trump adorn North Korea's newspapers, a significant propaganda victory which elevates Kim among his own people.

The fact that the talks are even happening also legitimises the regime internationally, and acknowledges North Korea's status as a nuclear-armed state.

In return, North Korea has made some sacrifices.

Siegfried Hecker is one of America's most respected nuclear scientists and one of the very few outsiders who has visited North Korea's nuclear facilities.

Hecker recently wrote in the Washington Post that, while the regime has built on its stocks of fissile material in 2018, meaning it could make more bombs, it has also ended its nuclear-weapons and ballistic missile tests, thus limiting its ability to actually fire a nuclear-tipped missile at an adversary and ensuring it detonates.

Overall, Hecker assessed that the threat had decreased in 2018.

What did America get from the Hanoi summit?

On the upside, the US was able to tell Pyongyang and the world that it was not desperate for a deal.

Trump, it seems, left the negotiating table when it was clear he was not going to get the kind of concessions he was asking for.

This may also quieten a few critics at home who insisted that Trump would make reckless concessions just for the sake of a photo op of him and Kim Jong Un signing a piece of paper.

Still, the Americans need this process, and need a deal, more than North Korea does. Why? Because time is on North Korea's side.

Yes, the additional sanctions imposed under Trump are hurting North Korea – the fact that Kim was prepared to decommission the Yongbyon reactor in exchange for sanctions relief tells us as much.

Yet Kim stopped short of making all the concessions Trump asked for, which in turns tells us that the sanctions, while painful, are not crippling.

And it's not like North Korea is unfamiliar with privation – poverty has been its lot for generations now, and the regime has survived.

Finally, Pyongyang always has the assurance that, if sanctions are ever tight enough to threaten the stability of the regime, China would provide economic relief because it doesn't want a failed state on its border.

So North Korea can afford to wait, but what about Washington?

To answer that question, it's worth recalling briefly how we got to this point. The answer is in four letters: ICBM, which stands for intercontinental ballistic missile.

Yes, North Korea has had nuclear weapons for years now, and America didn't like it. But what made that threat truly unbearable, what generated Trump's threats in 2017 and has now brought him to two rounds of talks is the fact that North Korea was testing a missile that could have delivered a nuclear payload onto a major US city.

That matters because it forces America's allies in Asia to confront a question which has a discomforting answer: is the US prepared to defend us against North Korea even if that means the possible loss of New York or Los Angeles?

North Korea has now halted testing so it is still unclear whether, in a crisis, it really could fire a missile that could reach the US, and if the warhead it is carrying would then survive re-entry and detonate over the target.

But the uncertainty alone may be enough to corrode America's alliances with South Korea and Japan.

The mere possibility that North Korea has an ICBM could slowly decouple America from its allies because the discomforting truth is that America is probably not prepared to take huge risks to its homeland for the sake of its allies.

In the Cold War, things were different. North Korea was then one part of a global Soviet-led threat to America's security and its values, so the US could credibly reassure its allies that it would defend them no matter what.

Now North Korea is diplomatically isolated and an economic basket case. South Korea and Japan, meanwhile, are both hugely successful and powerful, so the American people are entitled to ask why they should be prepared to make huge sacrifices to defend them.

The talks in Hanoi ended in stalemate, but the fundamental conditions that brought us to this point remain, and none of them favour America.

It cannot credibly threaten war, cannot impose enough economic pressure to coerce North Korea, and most importantly it cannot say with a straight face that this issue is important enough for it to risk a nuclear war that would destroy one or more American cities.