There was nothing to betray the feverish activity of North Korea's nuclear weapons scientists as our ancient Soviet-era Ilyushin-62 lumbered over emerald green paddy fields to the heart of the hermit state.
We saw women bent under firewood they were carrying along the unlit roads just outside the capital, Pyongyang, in scenes of unbelievable poverty.
North Korea's 23 million people have been in the grip of a paranoid Communist dictatorship since 1946. Instead of economic development, like South Korea, the leadership, under the country's revered founder Kim Il Sung, and his son Kim Jong Il, opted for repression and isolation.
They decided long ago to develop nuclear weapons as an insurance policy against the hostile states on their doorstep.
They did it secretly, burying research facilities inside impenetrable mountains and buying the hardware to build a bomb off the shelf in the international black market. They achieved this in the midst of a famine that killed unknown numbers, by accepting international aid and diverting it to the military.
The North Koreans had no trouble in finding willing assistants in the international community. In 1975, the young Pakistani scientist AQ Khan had returned home, after working at a uranium enrichment facility in the Netherlands, and was looking for customers.
Khan, who developed the world's first Islamic nuclear bomb for Pakistan in a top-secret programme, in the mid-1980s opened his own private "supermarket" of nuclear technology transfers in which he sold secrets to anyone who would pay.
One branch was based in his Pakistan laboratories, where four or six scientists were - perhaps unwittingly - involved. But the hub was in Dubai, which took care of procurement and distribution, with the help of European businessmen.
One flight from Pakistan to North Korea carrying conventional weapons was intercepted by the Pakistani government, acting on a tip-off that more sensitive material was on board. They found nothing - apparently because Khan's people were informed in advance.
Similar flights to Iran - which has confirmed receiving a centrifuge blueprint from Khan in the 1980s as part of a starter kit for its nuclear programme - also took place.
Through his network, Khan transferred to North Korea "nearly two dozen" P-1 centrifuges, and the more sophisticated P-11 centrifuges, according to President Musharraf, who debriefed the Pakistani scientist after his fall from grace. It has become apparent that North Korea was part of a global web of nuclear proliferation and was selling on to Iran.
By 1994, the Americans had become so worried about North Korea's clandestine programme that the Clinton administration signed a landmark agreement under which Pyongyang agreed to freeze its suspect nuclear weapons programme in return for two "safe" lightwater reactors for civilian purposes, and shipments of fuel.
That agreement, which fell apart after Clinton left office, set the stage for North Korea to play the nuclear card to blackmail the international community into shoring up its regime.
President Musharraf has recounted in his memoirs, In the Line of Fire, that he became suspicious as soon as he took over responsibility for Khan's activities in 1999.
Musharraf denies that there was a government-to- government deal with North Korea for the purchase of conventional ballistic missiles, including technology transfers for hard cash. But he says: "I received a report suggesting that some North Korean nuclear experts, under the guise of missile engineers, had arrived at Khan Research Laboratories and were being given secret briefings on centrifuges."
These are the spinning machines which enrich uranium to levels suitable for production of a nuclear weapon. Musharraf and the Pakistani intelligence chief confronted Khan and he denied the report, "but we remained apprehensive".
Once Khan had been confronted, however, his programme went further underground. "It was becoming clearer by now that AQ was not 'part of the problem' but 'the problem' itself," writes Musharraf.
In October 2002 the US learned that Pyongyang had a programme to enrich uranium for nuclear weapons, and ended fuel deliveries there. In December 2002 the UN inspectors were thrown out and, the following month, North Korea pulled out of the Nuclear Non-Proliferation treaty.
In February 2005 North Korea announced that it had manufactured nuclear weapons. But, until yesterday, it had never carried out a nuclear test.
The Democratic People's Republic of Korea
* Capital: Pyongyang
* Population: 22.9m with a life expectancy of 60 for men and 66 for women.
* Salary: Average monthly salary is £36
* Religion: Predominantly atheist.
* Politics: One of the last communist dictatorships.
Kim Il Sung became Great Leader after the Second World War. Since his death in 1994, the country has been run by his son Kim Jong Il .
* Human rights: It is estimated that there are 200,000 political prisoners. Reports of torture, slave labour and forced abortions and infanticide have emerged from prison camps.
* Life: Up to two million people have died from famines in the past 12 years. The country relies on foreign aid. The literacy rate is above 90 per cent and the main industries include military products and machine building.
* Media: Government-controlled radio and television has led to North Korea being judged the world's worst violator of press freedom by the media rights organisation, Reporter Without Frontiers.
War: North and South Korea are still at war. The threat of international war has been amplified by North Korea declaring its nuclear programme.
By Geneviève Roberts