Described as both a secret state and Stalinist nightmare, North Korea remains strictly quarantined from outside influences.
South Koreans reported the blast - but the North was silent
Its ruler, the mercurial Kim Jong-il, oversees one of the world's most repressive regimes, which is regularly accused of shocking human rights abuses.
For the country's 23 million people, life is hard, with many rural populations still struggling to recover from famine in the 1990s.
Even in the relatively affluent capital, Pyongyang, the sight of a foreign tourist or businessman is likely to trigger unease among North Koreans used to having every aspect of their daily lives liable to official scrutiny.
"North Korean people have little contact with the outside world," said Richard Willoughby, author of the Bradt travel guide to North Korea.
"They cannot get international TV, radio or newspapers," he said. "They do have domestic state press, but nothing too contentious is ever reported."
Mr Willoughby said the situation was improving, but the press was still essentially a government mouthpiece.
There are other restrictions, too, limiting the amount of information getting to North Koreans.
"Most people need permits to enter and leave the major cities," said Mr Willoughby.
Transportation is also very basic, even if people are able to get the necessary documentation.
"Few people have cars, there is no bus service, and the air services are extremely limited," Mr Willoughby said.
"The trains have improved in recent years, but they are still debilitated by a lack of fuel," he said.
Due to fuel sanctions from the US and neighbouring countries, North Korea suffers from a chronic electricity shortage.
It is not easy for North Koreans to meet foreigners either.
Kim Jong-il is worshipped as a virtual god in North Korea
Any prospective visitor must send their passport details in advance, as well as their curriculum vitae and a letter from their workplace.
And despite the emergence of mobile phones in some areas of the country in recent years, very few people have the ability to contact those overseas.
Jasper Becker, the author of a forthcoming book on North Korea called Rogue State, said that lack of information was just one of the hardships faced by ordinary people.
"North Korea is the most miserable place on Earth," he said. "Millions of people have starved to death since the economy collapsed in the mid 1980s."
"Hundreds of thousands are trying to escape the country's brutal regime, which controls people by fear."
North Korea's pariah-like status is only enhanced by its leader, Kim Jong-il, who is revered with almost god-like fervour.
Diplomats and escaped dissidents describe him as a vain, paranoid man, with a penchant for wrap-around sunglasses, Hollywood movies and French brandy.
But analysts are undecided what lies behind this facade.
Mr Willoughby said Mr Kim is more pragmatic than he may first appear, with his attempts at democratisation being stymied by a powerful military, which is worried about losing influence if there are changes to the status quo.
But Mr Becker had no good word to say for Mr Kim.
"He lives an incredibly extravagant lifestyle, and acts like a living god," he said. "He's the most evil ruler in the world today."