Mr Lim's statements could not be confirmed. North Korea may be on the brink of widespread social turmoil prompted by food shortages and disaffection with the Stalinist regime that could threaten security throughout East Asia. But it may not be in such dire straits. Nobody really knows.
Piecing together the scraps of information that emerge from the world's last hardline Communist state, the signs are that all is not well in Kim Il Sung's workers' paradise. And with the country apparently bent on using its clandestine nuclear weapons programme as its last bargaining chip with the outside world, its neighbours, particularly South Korea and Japan, are obliged to take Pyongyang seriously.
Despite heavy pressure from the US, Pyongyang is still resisting opening its nuclear research facilities to international inspectors. In May North Korea test-launched the Rodong 1 missile that would be capable of hitting much of Japan, and Mr Lim's stories of secret underground launching pads will only heighten tension across the Sea of Japan.
Mr Lim's testimony was made in Seoul, after he had been debriefed by South Korean intelligence. His story of a coup attempt against Kim Il Sung, after which he said 10 senior officers were executed, would be in line with the image of North Korea that the South would like to publicise. But his picture of an increasingly desperate regime coincides with other leaked evidence, causing fears in the region that civil strife within North Korea could precipitate a desperate last-gasp military venture by the regime.
For most citizens, food has clearly become a problem. Official posters now encourage people to eat only twice a day, and there have been repeated rumours of food riots in cities around the country. South Korean officials say that in many cases these 'riots' may be nothing more than a few people coming to blows over rice rations at the government warehouses, but they none the less show that people's tolerance is going down. Rice cannot be bought in North Korea - everyone receives a ration from the state, depending on their age and the type of work they do.
Agriculture, run along Stalinist collectivist lines, is inefficient, and has been further hit by the withdrawal of aid from China and the former Soviet Union, who had supplied large amounts of fertiliser. Harvests seem to be getting smaller each year. Earlier this summer it was announced that North Korea was to import 100,000 tons of rice from Thailand, although it was not clear how the impoverished regime would pay for the rice.
The North Korean media has vehemently denied rumours of food riots in the country, which according to Pyongyang watchers suggests they have something to hide. The media was particularly emphatic in denying reports of disturbances in April in the city of Shinuiju, which is close to the Chinese border. Traders who crossed the border told of widescale riots which were put down violently by soldiers. 'It is all a sheer lie,' said Radio Pyongyang. 'It's just like saying that a shower poured down from a sunny sky.' However, soon after North Korea stopped all cross-border trading with China.
Pyongyang has also stopped admitting foreigners, even Japanese of Korean origin who had been able to visit North Korea relatively easily by a special ferry that left Japan every 10 days. They brought consumer goods and hard currency that was welcomed by the regime, but since June the ferry has stopped taking passengers.