The official North Korean news agency, KCNA, released a bellicose statement Tuesday on behalf of the Korean People's Army supreme command, promising attack "without any notice" on South Korea over the "monstrous criminal act" offending Kim.
"Our retaliatory action will start without any notice from now as such thrice-cursed criminal act of hurting the dignity of the supreme leadership of the DPRK is being openly committed in the heart of Seoul under the patronage of the puppet authorities," the statement read.
Demanding an apology for "all anti-DPRK hostile acts, big and small," Pyongyang said military actions against targets immediately in "powerful sledge-hammer blows."
North Koreans celebrated Monday the birthday of Kim Il Sung, who launched the war splitting the peninsula.
South Korean officials said they have been monitoring their neighbor's military movements as it has operated joint exercises with U.S. allies.
An American helicopter made a hard landing near the border, 55 miles north of Seoul, early Tuesday, sparking yet another round of threats from Pyongyang.