Q&A: North Korea's nuclear threat
Six-nation talks on North Korea's controversial nuclear programme are underway in Beijing.
The BBC News website analyses the crisis over the North's nuclear ambitions, and examines the background to Western and Asian policy on the issue.
Do these talks matter?
Yes. The stand-off between North Korea and the US is possibly the most serious threat to East Asia's short- and long-term security.
With each month that passes, the risk of some misunderstanding or escalation increases, while North Korea claims to be using the time to add to its nuclear capability.
Despite such cause for urgency, little substantive progress was achieved at three rounds of talks which have taken place.
The US and North Korea, at least in public, appeared to be too far apart on the key issues to make any kind of breakthrough.
What do we know about North Korea's nuclear weapons programme?
North Korea claims to have nuclear weapons and to be working on building up its arsenal.
The problem for the rest of the world is that it is very difficult to verify these claims.
Most arms control experts suspect North Korea did pursue an active weapons programme - certainly up to 1994, when it signed a landmark agreement to freeze all nuclear-related activities.
But in December 2002, it restarted its nuclear reactor at Yongbyon and forced two UN nuclear monitors to leave the country.
It is unclear how far work has progressed at Yongbyon since then.
If the reactor were fully operational, some analysts believe it could produce enough plutonium to build approximately one weapon per year.
America's CIA says a separate, enriched uranium programme could be producing "two or more" bombs each year by the middle of this decade.
How many weapons does North Korea already possess?
This is very hard to say without full IAEA inspections. Experts believe that North Korea may have extracted sufficient plutonium for a small number of bombs.
US officials have put the number at "one or two".
About 8,000 spent fuel rods that were put into storage in 1994 could also be used to extract enough weapons-grade plutonium for a handful more weapons, the US believes.
North Korea has said it has already finished reprocessing these fuel rods, although South Korean and US intelligence are unsure whether to believe that claim.
What is this crisis really about?
Relations between the US and North Korea have deteriorated since President George W Bush labelled North Korea part of an "axis of evil" in January 2002.
Tensions really started escalating the following October, when the US accused North Korea of developing a secret, uranium-based nuclear weapons programme.
Washington is not only concerned about the development of such weapons in North Korea, but also wants to curb Pyongyang's capacity to export missile and nuclear technology to other states or organisations.
Since the October 2002 confrontation, North Korea has restarted a mothballed nuclear power station, thrown out inspectors from the UN's International Atomic Energy Agency and pulled out of the Nuclear Non-proliferation Treaty.
It has also upped its frequently doom-laden rhetoric, warning of the risk of nuclear war.
It is often very difficult to tell what lies behind North Korea's moves. Pyongyang and its mercurial leader Kim Jong-il act in erratic and contradictory ways.
But it seems possible that North Korea has been trying to use the nuclear issue as a hard-line ploy to negotiate a non-aggression pact and improved economic aid from the US.
Alternatively, the paranoid North may have decided the US intends to attack it anyway, and has been readying its defences while the US was preoccupied with places like Iraq.
Following Mr Bush's re-election, there were hopes the two sides could be brought back to the negotiating table.
North Korea's latest statement appears to rule out that chance for now.
Can diplomacy resolve it?
Maybe, but not easily.
Almost everyone - except North Korea - agrees the secretive state should not be allowed to continue with its nuclear weapons programme.
The difficulty will be finding enough diplomatic and economic carrots to persuade North Korea's leaders to give the programme up.
The Bush administration is especially wary because it says North Korea has already broken exactly that kind of nuclear deal - the 1994 Agreed Framework.
And although the North's most pressing problem is its moribund economy, Kim Jong-il's first concern is the survival of himself and his backers in the North Korean military.
From his perspective, he is being asked to give up his only guarantee against US attack, nuclear weapons.
Should we be worried?
Yes. Arms proliferation matters, especially when weapons of mass destruction fall into the hands of secretive, unpredictable regimes which may well be heading for catastrophic failure.
Many experts believe that the North Korean system is in terminal decline. Its people suffer great poverty and frequent famine. How the regime ends matters, and managing this potential crisis is made harder if it has nuclear arms.
There is also the danger that an unstable regime like this could provide such weaponry to third parties. North Korea already has a bad track-record in the proliferation of missile technology.
Hasn't North Korea threatened nuclear blackmail before?
Yes, in 1993. That time North Korea was persuaded to suspend its nuclear programme by negotiations which led to the 1994 agreement.
North Korea agreed to halt all its nuclear activities and in due course allow full inspections of its materials and facilities. In return it was to be supplied with heavy fuel oil and two power-generating reactors of a type less likely to prove a source of weapons-grade materials.
The reactors, which were to be supplied by an international consortium known as Kedo, were badly behind schedule when the latest crisis hit.
Their future is now uncertain.
What difference does the US see between North Korea and somewhere like Iraq?
They are different cases. North Korea is already an isolated regime with huge domestic problems. Two of America's regional allies - South Korea and Japan - have an active policy of engagement to try to win Pyongyang round to a more compliant line.
Perhaps more importantly, North Korea is believed to have the bomb, while Iraq did not. The view in the Bush administration is that action has to be taken before a country gets a nuclear capability. With North Korea it is just too late, so Washington has to manage the consequences as best it can.
------------------------------------------------------------------------
I don’t know why Kim Jong-Il would suddenly give up his favorite horse.
What the US offered???
Why does South Korea always give?
The BBC News website analyses the crisis over the North's nuclear ambitions, and examines the background to Western and Asian policy on the issue.
Do these talks matter?
Yes. The stand-off between North Korea and the US is possibly the most serious threat to East Asia's short- and long-term security.
With each month that passes, the risk of some misunderstanding or escalation increases, while North Korea claims to be using the time to add to its nuclear capability.
Despite such cause for urgency, little substantive progress was achieved at three rounds of talks which have taken place.
The US and North Korea, at least in public, appeared to be too far apart on the key issues to make any kind of breakthrough.
What do we know about North Korea's nuclear weapons programme?
North Korea claims to have nuclear weapons and to be working on building up its arsenal.
The problem for the rest of the world is that it is very difficult to verify these claims.
Most arms control experts suspect North Korea did pursue an active weapons programme - certainly up to 1994, when it signed a landmark agreement to freeze all nuclear-related activities.
But in December 2002, it restarted its nuclear reactor at Yongbyon and forced two UN nuclear monitors to leave the country.
It is unclear how far work has progressed at Yongbyon since then.
If the reactor were fully operational, some analysts believe it could produce enough plutonium to build approximately one weapon per year.
America's CIA says a separate, enriched uranium programme could be producing "two or more" bombs each year by the middle of this decade.
How many weapons does North Korea already possess?
This is very hard to say without full IAEA inspections. Experts believe that North Korea may have extracted sufficient plutonium for a small number of bombs.
US officials have put the number at "one or two".
About 8,000 spent fuel rods that were put into storage in 1994 could also be used to extract enough weapons-grade plutonium for a handful more weapons, the US believes.
North Korea has said it has already finished reprocessing these fuel rods, although South Korean and US intelligence are unsure whether to believe that claim.
What is this crisis really about?
Relations between the US and North Korea have deteriorated since President George W Bush labelled North Korea part of an "axis of evil" in January 2002.
Tensions really started escalating the following October, when the US accused North Korea of developing a secret, uranium-based nuclear weapons programme.
Washington is not only concerned about the development of such weapons in North Korea, but also wants to curb Pyongyang's capacity to export missile and nuclear technology to other states or organisations.
Since the October 2002 confrontation, North Korea has restarted a mothballed nuclear power station, thrown out inspectors from the UN's International Atomic Energy Agency and pulled out of the Nuclear Non-proliferation Treaty.
It has also upped its frequently doom-laden rhetoric, warning of the risk of nuclear war.
It is often very difficult to tell what lies behind North Korea's moves. Pyongyang and its mercurial leader Kim Jong-il act in erratic and contradictory ways.
But it seems possible that North Korea has been trying to use the nuclear issue as a hard-line ploy to negotiate a non-aggression pact and improved economic aid from the US.
Alternatively, the paranoid North may have decided the US intends to attack it anyway, and has been readying its defences while the US was preoccupied with places like Iraq.
Following Mr Bush's re-election, there were hopes the two sides could be brought back to the negotiating table.
North Korea's latest statement appears to rule out that chance for now.
Can diplomacy resolve it?
Maybe, but not easily.
Almost everyone - except North Korea - agrees the secretive state should not be allowed to continue with its nuclear weapons programme.
The difficulty will be finding enough diplomatic and economic carrots to persuade North Korea's leaders to give the programme up.
The Bush administration is especially wary because it says North Korea has already broken exactly that kind of nuclear deal - the 1994 Agreed Framework.
And although the North's most pressing problem is its moribund economy, Kim Jong-il's first concern is the survival of himself and his backers in the North Korean military.
From his perspective, he is being asked to give up his only guarantee against US attack, nuclear weapons.
Should we be worried?
Yes. Arms proliferation matters, especially when weapons of mass destruction fall into the hands of secretive, unpredictable regimes which may well be heading for catastrophic failure.
Many experts believe that the North Korean system is in terminal decline. Its people suffer great poverty and frequent famine. How the regime ends matters, and managing this potential crisis is made harder if it has nuclear arms.
There is also the danger that an unstable regime like this could provide such weaponry to third parties. North Korea already has a bad track-record in the proliferation of missile technology.
Hasn't North Korea threatened nuclear blackmail before?
Yes, in 1993. That time North Korea was persuaded to suspend its nuclear programme by negotiations which led to the 1994 agreement.
North Korea agreed to halt all its nuclear activities and in due course allow full inspections of its materials and facilities. In return it was to be supplied with heavy fuel oil and two power-generating reactors of a type less likely to prove a source of weapons-grade materials.
The reactors, which were to be supplied by an international consortium known as Kedo, were badly behind schedule when the latest crisis hit.
Their future is now uncertain.
What difference does the US see between North Korea and somewhere like Iraq?
They are different cases. North Korea is already an isolated regime with huge domestic problems. Two of America's regional allies - South Korea and Japan - have an active policy of engagement to try to win Pyongyang round to a more compliant line.
Perhaps more importantly, North Korea is believed to have the bomb, while Iraq did not. The view in the Bush administration is that action has to be taken before a country gets a nuclear capability. With North Korea it is just too late, so Washington has to manage the consequences as best it can.
------------------------------------------------------------------------
I don’t know why Kim Jong-Il would suddenly give up his favorite horse.
What the US offered???
Why does South Korea always give?