North Korea is aptly described as a communist police state. But it is more than that, it is a Stalinist communist police state. The difference was that Stalin, who ruled the Soviet Union from 1922, to his death (from natural causes) in 1953, made great use of terror to maintain control. He killed over 20 million of his subjects. Most died from starvation (he cut off the food supplies to regions he suspected of disloyalty) or from disease and hunger in prison camps (where he sent over 14 million people he mistrusted) or while entire ethnic groups were forcibly relocated to other parts of the country. He certainly terrified the population, and his subordinates in the government. But as soon as Stalin was dead, his most senior officials quickly met and agreed to end the reign of terror. Several of Stalin's key security officials were arrested and executed, and thousands more were jailed or just dismissed. The new leadership was hesitant to admit that their Great Leader Stalin had been in error. But, starting in 1956, the new leader, Nikita S. Khrushchev, began giving the "secret speech" to the Communist Party leadership, explaining why Stalin's terror apparatus was dismantled (this was soon leaked to the general public, and was widely popular with most Soviet citizens). While the secret speech did not remain secret for long, not everyone drew the same conclusions.
When Kim Il Sung was placed in control (by Joseph Stalin) of North Korea in 1945, he was advised to use his mentor's methods to maintain control. Kim Il Sung proceeded to set up his own prison camps and executed thousands of officials whose loyalty was suspect. After Kim Il Sung died in 1994, his 52 year old son, Kim Jong Il took over. He was his father's son when it came to using Stalinist tactics. Actually, two years before his father died, Kim Jong Il ordered the execution of twenty officers and fired 300 others, just on suspicion of disloyalty. After his father died, Kim Jong Il killed or dismissed (often to a prison camp) thousands more. Most of these victims were scapegoats for the great famine of the 1990s (brought about by Russia halting its economic aid, bad weather and, most of all, the ineptitude of the communist planned economy.)
Since the 1990s, no one in North Korea has had any doubt that Kim Jong Il has an itchy trigger finger. This was definitely all about, "it is better to be feared than loved." Although called the "Dear Leader," Kim Jong Il was anything but cuddly. This was demonstrated this year when, in the wake of a disastrous currency reform (that ruined the market system that was keeping many Koreans alive) last November, Kim had several key economic officials publicly executed. Hundreds of other officials have been fired or retired.
In the end, what this means is that the only way to remove Kim Jong Il from power is via violence, including killing Kim. Since Kim Jong Il has extremely tight security around himself, he, like his father, will probably die in bed (probably sooner rather than later, as the Dear Leader has not been well of late.) Unlike his father, Kim Jong Il does not have a competent son standing by to take over. His most capable son is the youngest, a sharp lad in his 20s. This is too young, and inexperienced, to handle the many hardened old timers that fill the upper ranks of the North Korean government. It looks like there may be another Secret Speech in the making.