When North Korea announced for the first time in February 2005 that it had nuclear weapons, the claim was dismissed by the Bush administration as bluster and "rhetoric".
"North Korea's words and actions will only deepen their international isolation," Scott McClellan, the then White House spokesman, told reporters.
Eighteen months later, on October 6, 2006, the high-stakes poker game reached a critical point as North Korea called Washington's bluff and conducted its first nuclear test.
Whether that test was a success or not remains a matter of debate.
Some estimates have put the yield at less than a kilotonne – a relatively small blast in nuclear terms, leading to speculation that the main component of the device failed to detonate.
Dud or not, the political shockwaves from the underground blast were felt far and wide.
Now, almost a year and a half later, North Korea has conducted a second and reportedly much larger test – a gesture of defiance just two months after it triggered international outrage with its launch of a long-range rocket.
That combination – long-range rockets, plus atomic explosives - has many worried.
But exactly what kind of a threat does North Korea pose?
Ron Huisken, a nuclear non-proliferation expert at the Australian National University, says that the latest test is a signal the North is committed to retaining its nuclear capability.
But, he says, it does not in itself prove North Korea is a clear and present nuclear danger.
"North Korea can't actually do anything at this point," he told Al Jazeera.
"To the best of our knowledge, it hasn't actually weaponised its nuclear material. Certainly it hasn't miniaturised it to the point where you can put a bomb on an airplane or – even more technically demanding – on top of a missile."
|The Yongbyon reactor is believed to have produced plutonium for about eight bombs
According to US estimates North Korea has extracted enough plutonium to build six to eight nuclear bombs.
The North itself has repeatedly referred to a nuclear "stockpile", which it says serves as a "deterrent" against what it sees as the imminent threat of US invasion.
Its nuclear plant at Yongbyon, which is believed to have resumed operations after the North abandoned six-party disarmament talks in April, is thought to be capable of producing enough plutonium for about one more bomb a year.
That may be the case, but it is important to bear in mind that much of what is said to be "known" about North Korea's nuclear programme is based on very limited intelligence.
Those limitations were shown most recently by the apparent ease with which the North – one of the world's poorest countries - was able to take the rest of the world by surprise with its latest test.
John Large, a UK-based nuclear analyst and engineer, says a key factor to watch in the coming weeks will be whether the North conducts more nuclear tests. In particular whether it matches them with further tests of long-range missile technology.
|North Korea is not thought to have weaponised its nuclear devices to fit on missiles [AFP]
"If now we see a succession of tests, that will suggest that there's a development programme of the weapon itself towards the final production model - and trying to match the weapon to a delivery system," he told Al Jazeera.
"Put those two together and the threat from North Korea becomes very, very real."
For the time being though estimates on the size of North Korea's nuclear arsenal remain just that – estimates.
No outsider has ever seen a North Korean nuclear device and no photographs have been released.
As a result, few beyond the most senior North Korean officials have any idea what form North Korea's nuclear weapons are in or where they are kept.
Indeed, the issue of what to do with the weapons "stockpile" the North supposedly already has proved so complex and cloaked in secrecy that it was largely sidelined in the six-party disarmament talks.
With the Bush administration desperate to secure a foreign policy success in its final months, US negotiators repeatedly scaled back on what aspects of its weapons programme North Korea was expected to declare.
With Pyongyang now apparently having turned its back on the six-nation talks, the condition, location and usability of its alleged arsenal is even more confused and uncertain.
|North Korea is a highly militarised and deeply paranoid society [EPA]
In addition while North Korea may not itself have mastered the processes of weaponising its nuclear devices, questions remain over whether it might have acquired that technology from elsewhere - perhaps using its own proven missile technology as a bargaining chip.
Western intelligence officials have focused attention on alleged co-operation between North Korea and Pakistan, with suggestions that Pakistani scientists may have offered assistance in warhead design in return for the North's missile know-how.
Then there is the question of how secure North Korea's alleged nuclear "stockpile" actually is.
That raises the possibility of what counter-proliferation experts call the "loose nukes" scenario – the prospect that a cash-strapped North Korea, or a North Korean official, might secretly sell one or more of its bombs to anyone willing to pay.
Beyond that there is the broader perception factor - how North Korea's apparent determination to retain and expand its nuclear arsenal will be seen and interpreted by its neighbours.
John Large, the UK-based nuclear analyst, says North Korea's latest steps - particularly if it is followed by further nuclear tests - could trigger a regional nuclear arms race.
"The problem is that you have two powers in particular that are not yet nuclear powers but could very easily be – Japan and South Korea," he told Al Jazeera.
"And the historic antagonism between Japan and the Korean peninsula is well established."
With Japan already in possession of a sophisticated civilian nuclear programme, Large says the general consensus is that Japan, if it felt sufficiently threatened, could develop its own atomic weapons within a matter of months.
If Japan goes down the nuclear road others in the region would be under pressure to follow suit, raising the stakes once again for an already deeply paranoid North Korea.
|North Korea has said it needs a nuclear deterrent to defend against US invasion [AFP]
Having isolated itself from the world for more than half a century, North Korea has become a master of secrecy and deception.
Unpredictability is its most powerful weapon.
For years it has been widely accepted that what North Korea craves is attention and recognition.
Most importantly, so the thinking goes, it craves recognition from and direct talks with the US.
But that is not all North Korea wants - it also wants to survive.
North Korea's leaders and its most senior military commanders have too much at stake to risk the collapse of the secretive, highly militarised, and deeply paranoid state over which they rule.
North Korea is a country built on illusion, lies, half truths and propaganda - reality comes a long way down the list.
But that does not mean it is not a danger.
The more belligerent it becomes, the more agreements it scraps, the more talks it walks away from, the less likely it is that the process of peaceful disarmament remains an option.
To date, only one country in history has actually given up a weapons programme that had successfully produced atomic weapons.
That country was South Africa, which ran a secret weapons development programme in the 1970s and 80s, the height of the apartheid era, producing six uranium-based weapons.
The programme was admitted to only in 1993, after the bombs had been disassembled and production facilities destroyed; and as South Africa - a relatively prosperous and stable country - made its transition to democratic rule.
For a country as diplomatically isolated and impoverished as North Korea, nuclear weapons are its sole trump card.