Troops entered Czechoslovakia without anti-tank missiles or gun training, later purging editors and hunting "terrorists" after NSO Nikolov was kidnapped and murdered.
North Korea secretly targeted Prague for uranium-mining gear and a reactor while diplomats in Geneva fought to freeze the nuclear map during the mid-1960s.
Prague feared North Korea was equipping itself with nuclear weapons and risking global war while Budapest dismissed the alarm as a tactic to sound out Jimmy Carter's plans.
Czechoslovakia and East Germany blocked students from accessing state secrets in nuclear physics after Pyongyang urgently offered to pay all costs for 95 trainees.
Historians spent a decade sorting through wreckage from a state security apparatus to determine how the transition from 41 years of one-party rule actually functioned on paper.