In June 1994, the United States and North Korea came very close to war.
Speaking to a gathering of policy-makers in Washington last month, William Perry, then defence secretary, noted that "we came much closer to a war then than most people in this room probably appreciate."
He went on to say: "We were willing to risk war because we believed that a nuclear weapon production programme in North Korea posed an unacceptable security risk" for the US and its allies.
That risk is even more real today. The present crisis with North Korea is seen, in some ways, as being very much a repeat of 1994.
But the stakes are even higher. In December 2002, North Korea announced it was restarting its one functional reactor, and re-opening other nuclear facilities frozen under the international agreement that ended the 1994 stand-off.
Since then - according to US officials - the North Korean authorities have made it clear that they have begun reprocessing spent fuel rods, which will provide enough plutonium to make several nuclear weapons.
According to US officials, N Korea has admitted reprocessing fuel rods
Some reports indicate that North Korea may already have a small number of these weapons.
So is it too late to prevent the reclusive country from becoming a fully-fledged and declared nuclear weapons state?
And how far, given the Bush Administration's recent experience in Iraq, is there really a US military option on the Korean Peninsula?
No clear boundaries
North Korea has still not tested a nuclear weapon, and there are hints that its programmes could well be up for negotiation if the conditions are right.
The Bush administration's diplomacy is seen by most North Korea watchers as sloppy.
For a long time it seemed to have disengaged from the problem, doing little to encourage the North Koreans into further talks. More recently it has also been distracted by Iraq.
But there has been a failure, not just to engage, but also to set clear red lines or limits that the North Koreans would cross at their peril.
This uncertainty is part of the explanation for the fact that America's allies in the region - notably South Korea and Japan - are by no means in step with the Bush administration's views.
About 37,500 US troops are based in South Korea
There is no doubt though, among US strategic thinkers, that a nuclear North Korea would be a security disaster, and could well pose the "unacceptable risks" cited by Bill Perry.
The US view is that the possession of nuclear weapons might lead Pyongyang to under-estimate Washington's commitment to South Korea, perhaps making war more likely.
It could lead to a domino effect of proliferation in East Asia, as other countries in the region seek their own deterrent - something that China, especially, wants to avoid.
If the North Koreans follow their existing pattern of behaviour concerning the sale of long-range missiles, then bombs or fissile material could be up for sale to the highest bidder.
And eventually, if the North Korean regime collapses, there would be a further proliferation danger. Weapons or nuclear material could again fall into the wrong hands.
Most US experts insist that any answer to the North Koran nuclear problem must be diplomatic.
But there is an equal belief that diplomacy must be backed up by a credible military threat.
That in large part explains the recently announced US troop re-deployment in South Korea.
This has been in the works for some time.
The US has some 37,500 servicemen and women in South Korea.
The 14,000-strong US Second Infantry Division has always been deployed close to the demilitarised zone separating the North and the South, to act as a sort of deterrent tripwire.
But the Pentagon's current view is that keeping such forces in an area that could be saturated with North Korean artillery fire is no deterrent at all.
Better to move their bases south, from where they could move to respond to any North Korean attack.
But what of a US pre-emptive military move? Pre-emption, after all, is the new Bush strategic doctrine.
The US re-deployment, which will take some years, could also be seen in this light - as a means of giving planners more options.
But there is nonetheless a broad understanding at all levels of the Pentagon that a war in Korea would be an appalling prospect, and would lead to hundreds of thousands of casualties, even if nuclear weapons were not used.