read it about three times

Andrei Lankov is little bit sceptical.

North Korean intelligence official tells of aborted coups and assassination attempts:
One of only a handful of North Korean intelligence officials ever to have escaped the country, according to Telegraph, paints a dark portrait of plotting and factions in Pyongyang.
The official, who asked to be named only as Mr K, said he had personal knowledge of two assassination attempts on Kim Jong-il, who ruled North Korea from 1994 until his death in December 2011.
In one attempt, a lone gunman with an automatic weapon attempted to shoot him, but was captured before firing. In another, a would-be assassin driving a 20-ton lorry rammed his motorcade but failed to kill Kim Jong-il, whose car was in a convoy of identical limousines and was not among those damaged.
In an extraordinarily rare behind-closed-doors breifing, the official also detailed two attempted coups against the regime, following uprisings in the Korean People's Army, especially among the officers who had been trained in the former Soviet Union.

The two assassination attempts on Kim Jong-il, shortly before he took over as leader from his father, Kim Il-sung, help to explain his subsequent paranoia, and his preference for travelling by private, armoured, train, the intelligence official said.
Mr K said that while North Korean agents are present among South Korea's 25,000-strong community of defectors, he does not fear assassination.
We have no one chain of collaborative evidence, said Andrei Lankov, a North Korean expert at Seoul's Kookmin University. But this does not mean conspiracies did not exist.
Still for example, this adds up.
Then in 1997, for reasons that were at the time unexplained, the regime sent troops into the headquarters of the army's Sixth Corps, prompting firefights and arrests. The corps was subsequently disbanded.
Describing the country's internal security system, Mr K - who fled the country in 2005 - said that even the most senior cadres and army generals were routinely monitored, often by agents posing as their chauffeurs, and their activities reported to the Supreme Leader in weekly bulletins.