First and fundamentally, this has been since 1950 a conflict between the US and China, as much as it has been between North and South Koreans. I don’t think the Americans trying to tidy up the Pacific War in 1950 expected the newly-minted Maoist government in China to make such a feisty fuss about their plans to stabilise Korea with a “Pax Americana” (as they had Japan).

The armistice in 1953 that divided the country along the 38th Parallel was synthetic and probably no one at the time expected the line to stay in place for very long. No peace was ever formally signed, so to this day, all protagonists in formal terms remain at war.

For most of the past six decades, what the Koreans wanted for themselves was largely irrelevant. The malevolence and suspicion that prevailed between the US and China ensured that North Korea remained in place largely as a buffer keeping US troops as far as possible away from China’s 1,400km border with North Korea. Even for the US, committed to the defence of South Korea, the eccentric Kim dynasty to the North also provided an important buffer, keeping China’s troops at arm’s length from Seoul.

It is a deep and tragic irony that as relations between the US and China have improved over the past three decades, with China’s leaders becoming much less dogmatic, confrontational or Communist, so the unattended passage of time has allowed the hermit Kim dynasty, and the military elite that underpins it, to throw down roots and imagine a future of their own.

Most Koreans over the past six decades have openly but disingenuously cherished the idea of reunification. For most observers, up to this day, this implicitly meant the wealthy South Koreans assuming power and control over the impoverished North. After all, in 2016, North Korea’s GDP of US$28.5 billion was a piffling 2 per cent of South Korea’s US$1.4 trillion. Its exports, worth less than US$3 billion and mainly to China, are worth barely half of one per cent of South Korea’s US$495 billion.

But in recent years – and in particular since Kim Jung-un was anointed in April 2012 – it seems the North Korean’s have begun to imagine a different future. Alongside the fear-driven belief that “nuclear deterrence serves as the strongest treasured sword” – protecting Kim and his regime from the US enemy and the ignominious fate of Gaddafi in Libya and Saddam Hussein in Iraq – the regime has developed a second strategic track, known as the “byungjin line”, which involves economic development, nurturing a private sector and functioning markets (called jangmadang) and raising wages.

Implicit in this development appears to be a belief that in due course Pyongyang could re-unify the divided country on its own (nuclear) terms. The primary adversary – the US – would have to be persuaded to withdraw its troops from the south – hence the targeting of missiles at Guam and mainland US targets. No wonder so many military strategists can no longer sleep comfortably at night.

For the US, Japan and of course South Korea, this shift has profoundly altered views about future strategic options. A policy of containment no longer meets the challenge of a nuclear-armed North Korea with ambitions to reconquer the south – but at the same time Donald Trump’s threat to respond pre-emptively is naive and would be catastrophic: within milliseconds of pressing the button to launch missiles at targets in North Korea, Kim’s men would launch in the opposite direction.

Any missiles launched towards Japan or Guam could perhaps be diverted or destroyed, but nothing could avert catastrophe in Seoul, with millions of immediate casualties. Trump and the US military know this, and an attack on Pyongyang undertaken in the full knowledge that collateral damage would involve so many deaths in Seoul would rightly be seen as an absolute betrayal of one of the US’s closest allies. The idea of “Better a Korean peninsula in flames than San Francisco” – as one Post columnist put it earlier this week – might seem sad but sensible in certain corners of the Pentagon, but would destroy confidence worldwide in the US as an ally.

China has been mightily disconcerted by these dramatic recent developments, but sticks at present to its long-standing “Three Nos” policy: No nuclearisation; No war; No chaos”. The bottom line here is no US troops stationed along its Liaoning and Jilin borders. But one senses that China’s long-standing support for Kim must now be in question.

What future does all this imply? On balance, it means at least five things:

•The US will not start a war, but with luck has the hacking and jamming technologies needed to stop North Korean weapons from doing harm;

•Regime change in North Korea is increasingly likely, probably engineered by China;

•There will be no reunification any time soon, and this would anyway never be acceptable to China without linked US commitments to withdraw eventually from the peninsula;

•Since a nuclear-armed North is now a reality we probably have to live with, this might involve the South getting nuclear technology too;

•All this can only happen with close cooperation, and improved relations between China and the US in the long term.

But then, I could be completely wrong. In which case, please find the nearest bunker.

David Dodwell researches and writes about global, regional and Hong Kong challenges from a Hong Kong point of view