North Korea has accused the US and South Korean spy agencies of an unsuccessful assassination attempt on leader Kim Jong Un involving bio-chemical weapons.
North Korea's Ministry of State Security said it will "ferret out and mercilessly destroy" the "terrorists" in the CIA and South Korean intelligence agency for targeting its supreme leadership.
North Korea frequently lambasts the United States and South Korea, but this accusation is unusual in its details.
The ministry said the spy agencies "ideologically corrupted and bribed" a North Korean citizen who had been working in Russia to carry out the alleged assassination attempt involving a "radioactive" and "nano-poisonous" substance.
It said South Korean agents gave $20,000 (€18k) and satellite communication equipment to the North Korean to attack Kim during a public event with a bio-chemical weapon.
The ministry threatened that a counter-attack would begin immediately.
"Korean-style anti-terrorist attack will be commenced from this moment to sweep away the intelligence and plot-breeding organisations of the US imperialists and the puppet clique," it said, referring to South Korea.