It is as officially confirmed as such things will ever be: America's intelligence community now estimates that North Korea will succeed in producing a "reliable, nuclear-capable" intercontinental ballistic missile able to hit the territory of the United States as early as next year.

That will not mean that North Korea has mastered all the technology required to be a global nuclear power. Apart from providing photographs of a curious object that looked like a disco ball of 1950s vintage, Pyongyang has yet to demonstrate its ability to build a miniaturised warhead to fit on its long-range missiles. Nor is it obvious that it has successfully dealt with the challenge of designing a missile that can pass through the earth's atmosphere without damaging its nuclear warhead, another essential requirement for a country which claims to be able to hit at the US.

Still, the realisation that the North Koreans are far more advanced in their nuclear quest than any previous intelligence agency ever thought likely only brings nearer the moment when the president of the United States will have to make the binary decision all American leaders over the past quarter of a century have tried to avoid: whether to launch a highly risky pre-emptive strike against North Korea's nuclear arsenal, or accept North Korea's nuclear status.

Either way, Asia's security map is likely to be profoundly altered. And such changes could become a reality in less than 12 months from now.

Western intelligence agencies have persistently failed to gauge correctly the speed of every successful nuclear programme undertaken by any nation. The Americans were taken by surprise when the Soviets detonated their first nuclear charge in 1949, when the French detonated theirs in 1960, when Israel acquired a nuclear capability during the late 1960s, when India followed suit a decade later, or when Pakistan became a fully fledged nuclear power in the 1990s. At each stage, the belief was that, for one reason or another, the respective country was not yet ready to join the nuclear club.

In this respect, therefore, the apparent failure to assess correctly the progress made by North Korea is not exceptional; it is the norm in such situations. And that is not because intelligence agencies are not intelligent enough, for major Western countries have poured huge resources into counter-proliferation measures and their spies are very good at detecting secret nuclear programmes at the earliest stage of their inception; just ask Iraq, Iran, Syria, Taiwan, South Korea, Brazil, Argentina and South Africa, all of whom were stopped in their tracks.

Rather, the failure to assess the speed of a nuclear programme is due to the practical difficulties of estimating scientific progress. It is very tricky to calculate how good a country's scientists may be in mastering nuclear knowledge, and particularly in leapfrogging technical hurdles by mixing existing technologies with imaginative shortcut solutions nobody thought of before.

And it is equally difficult to predict how fast knowledge flows into a nuclear programme. Currently, intelligence analysts are still debating whether the speedy strides in missile technology which North Korea is registering are due to technological developments achieved in the past and merely made public now, or to some new technological breakthroughs made, bought or perhaps stolen by Pyongyang more recently.

Yet, while the failure to track every twist of North Korea's march to nuclear status remains understandable, it should also give pause to those in Washington who may be tempted to advocate a pre-emptive US military strike against Pyongyang's nuclear arsenal. For it may be difficult to be certain that both the equipment and the knowledge can be destroyed in one fell swoop, given the fact that North Korea has been engaged in this programme for about half a century.

And that is before one considers the other big danger with a pre-emptive strike: the risk of North Korea's deadly retaliation, perhaps by unleashing a massive conventional missile and artillery barrage on Seoul, the South Korean capital, where up to 70,000 people may perish within the first few hours of conflict.

But without such a pre-emptive strike, the only other alternative facing the US is to accept North Korea's nuclear status, and move to a posture of deterrence against the North Korean regime. And that is precisely what armies of academics and think-tankers are now advocating.

COST OF DETERRENCE

They argue that just as the US operated a policy of deterrence with the Soviet Union during the days of the Cold War or with Russia and China today, it could do the same with North Korea.

The threat of mutually assured destruction in case of a nuclear exchange may not be a pleasant one to contemplate, but it has prevented any nuclear war, to the point that nuclear bombs are now largely considered as political, rather than military-operational weapons - they are there to make a statement that their possessor cannot be interfered with or ultimately defeated, rather than to be actually fired.

The standard retort, that North Korea's leader is not rational and that, therefore, deterrence will not work with him, is almost certainly wrong. For although Mr Kim Jong Un and his regime are decidedly odd, there is a perfectly rational logic to their nuclear quest. And neither him nor his father or grandfather could have possibly thought that they could win a nuclear exchange with the US; in all likelihood, what they are really seeking by getting the bomb is safety against a regime change or the overthrow of their rule, an objective that is perfectly compatible and achievable with deterrence theories.

Still, the problems with a deterrence stand-off between the US and North Korea remain formidable. The first is the matter of political acceptability: Would the US public and American legislators accept entering into a mutually assured destruction arrangement with Mr Kim without a murmur? Unlikely, given the current mood in Washington; Senator Lindsey Graham has already gone on record saying that he prefers a pre-emptive strike against North Korea even if this means a war on the peninsula, since everything must be done to prevent a war on US territory.

Furthermore, would the Europeans also accept a deterrence posture to North Korea, since London is the same distance from Pyongyang as the Western coast of the US?

And would America's so-called "extended deterrence", the nuclear umbrella it provides not only to its key regional allies of Japan and South Korea, but also Australia, remain credible? Could military planners in these Asian countries truly believe that, should they be attacked by North Korea, the US would risk a nuclear war on their behalf? Would, in short, President Donald Trump be prepared to sacrifice Seattle for Sapporo? Unless that answer is clear and persuasive, the temptation among key Asian countries to acquire their own nuclear weapons will become irresistible.

But the biggest problem in a deterrence strategy with Pyongyang is that it will not provide much stability. The idea that deterrence ensures stability is largely a myth, for while it prevents a nuclear exchange, it promotes other confrontations. Few Europeans and no Americans died fighting in Europe during the four decades of the Cold War, but tens of millions of Africans, Asians and Latin Americans died in proxy wars conducted by the Soviet Union and the West as the two camps were deterring each other. The same happens today: Nuclear deterrence works well between the US and China, but that does not prevent risk-taking by both sides in Asia and, increasingly, elsewhere in the world.

Mr Kim may adopt the same approach; once he is accepted into the nuclear club, he will use this status to up his blackmailing games for food and money, demand the lifting of sanctions, and undertake other reckless risks against South Korea, Japan or further afield.

And it is equally a myth to believe that, once it is accepted as a nuclear power, Pyongyang's nuclear quest will stop. In fact, just the contrary: North Korea will seek to acquire a second-strike nuclear capability to ensure against a surprise US attack, and may begin to see a direct rival in China as well. So, Pyongyang's capabilities for threatening its immediate neighbours will continue to grow, and its nuclear arsenal may expand from 13 to 30 nuclear warheads now to perhaps 100 by the middle of the next decade. That is stability, but only for twisted minds.

In short, whichever way one turns, the prospects for security in Asia in the aftermath of a fully fledged nuclear North Korea are grim.

And future generations will no doubt wonder how all of us sat, watched and debated such terrible developments, but failed to prevent them.