For the moment the simple answer is that only North Korea knows – and only a very select few North Koreans at that.
North Korea's long-delayed declaration of its nuclear weapons programme is not expected to shed any light on the eight or so plutonium-based bombs it is alleged to have built.
The declaration document has been seen as a crucial step in North Korea's nuclear disarmament.
But in the months since the original end-of-2007 deadline was missed the US has repeatedly scaled back expectations for what it should contain.
The declaration, for example, is not expected to do anything more than "acknowledge" US concerns over an alleged uranium enrichment programme – the dispute that originally sparked the current standoff in 2002.
It will also give no details on what exactly North Korea plans to do with the bombs it supposedly already has.
That has been left to an undetermined next stage of the six-nation disarmament talks, when the North is due to agree to a schedule and process for abandoning and dismantling all of its nuclear weapons.
"The North Koreans have acknowledged that we have to deal with the weapons," Christopher Hill, the chief US nuclear negotiator, said in Beijing this week.
"We're going to deal with it as soon as we sit down again to map out the remaining piece of this negotiation."
But for a country as diplomatically isolated and impoverished as North Korea, its nuclear weapons - if indeed it has them - are its sole trump card.
|It is unclear whether North Korea has the ability to deliver a nuclear weapon [AFP]
How easily it might be persuaded to part with them is far from clear.
To date only one country has actually given up a weapons programme that had successfully produced atomic weapons.
That country was South Africa, which ran a top secret weapons development programme in the 1970s and 80s, the height of the apartheid era.
The programme produced six uranium-based weapons but was only admitted to in March 1993, after the bombs themselves had been disassembled and production facilities destroyed – a process that was later verified by the UN.
As for the North Korean bombs, little is known about them other than that they are believed to exist in some form or another.
According to US estimates the North has produced enough plutonium for at least eight bombs.
But these estimates are just that: estimates. No international inspector has ever been shown an actual North Korean nuclear device or even a photograph.
North Korea itself has admitted to owning a nuclear "stockpile" and has previously threatened to use it; warning, for example, of its ability to turn South Korea into a "sea of fire".
|North Korea has threatened to turn the South into a "sea of fire' [GALLO/GETTY]
But where these bombs are kept and what form they are in is, again, purely speculation.
Western intelligence officials doubt that the bombs, if they exist, are in any kind of easily deliverable form – for example, small enough to be launched atop a missile or carried on an aircraft.
Nuclear experts say that building a basic atomic weapon is relatively easy compared to mastering the miniaturisation processes involved in turning the bomb into something that can actually be used against an enemy target.
But while North Korea may not itself have mastered those processes, questions remain over whether it might have acquired that technology from elsewhere, perhaps using its own missile technology as a bargaining chip.
Western intelligence officials have focused attention on alleged co-operation between North Korea and Pakistan, with suggestions that Pakistan may have offered assistance in warhead design in return for North Korean missile know-how.
Then there is the question of how secure North Korea's alleged nuclear devices actually are.
For some US officials the security of these weapons raises the possibility of the so-called "loose nukes" scenario – the prospect that a cash-strapped North Korea might secretly sell one or more of its bombs to anyone willing to pay.