The ministry of state, which published details of the alleged scheme in a statement that ran close to 2,000 words, said North Korea would ferret out the backers “even by ransacking the whole earth”.
"The Central Intelligence Agency of the U.S. and the Intelligence Service (IS) of south Korea, hotbed of evils in the world, hatched a vicious plot to hurt the supreme leadership of the DPRK and those acts have been put into the extremely serious phase of implementation after crossing the threshold of the DPRK," the North's KCNA news agency quoted the statement as saying, referring to the North by its official name, the Democratic People's Republic of Korea.
"A hideous terrorists' group, which the CIA and the IS infiltrated into the DPRK on the basis of covert and meticulous preparations to commit state-sponsored terrorism against the supreme leadership of the DPRK by use of bio-chemical substance, has been recently detected."
CNA said the two intelligence services "ideologically corrupted" and bribed a North Korean surnamed Kim and turned him into "a terrorist full of repugnance and revenge against the supreme leadership of the DPRK".
"They hatched a plot of letting human scum Kim commit bomb terrorism targeting the supreme leadership during events at the Kumsusan Palace of the Sun and at military parade and public procession after his return home," KCNA said.
"They told him that assassination by use of biochemical substances including radioactive substance and nano poisonous substance is the best method that does not require access to the target, their lethal results will appear after six or twelve months...
"Then they handed him over $20,000 on two occasions and a satellite transmitter-receiver and let him get versed in it."
North Korea conducted an annual military parade, featuring a display of missiles and overseen by top leader Kim Jong Un and his right-hand men on April 15 and then a large, live-fire artillery drill 10 days later.
CIA apologists are talking to the media and denying that such an attempt would be made. But President Trump clearly wants to get Jong Un and the CIA has a history of failed assassination attempts.