The plot was said to have involved an assassin named "Kim," who was allegedly paid $40,000 by the CIA to use radioactive material to kill the supreme leader during North Korea's Day of the Sun parade.

"They told him that assassination by use of biochemical substances including radioactive substance and nano poisonous substance is the best method," said state broadcaster KCNA.

"Then they handed him over $20,000 on two occasions and a satellite transmitter-receiver and let him get [started]."