This essay explores the cinematic Cold War in 1960s South Korea, focusing on a popular film, The Great Monster Yonggari (Taegoesu Yonggari, 1967), and its transnational production, circulation, and responses. Initially produced as a children’s movie by Korean film director Kim Kidŏk, Yonggari had great success at the box office in South Korea. Later, with cooperation and international marketing by the Japanese company Toei, this film was introduced by American International Pictures television in the United States in 1969 with the title Yongary, Monster from the Deep. The transnational cultural nexus in the production and distribution of The Great Monster Yonggari obviously reflects the global Cold War politics among the nations in the “free world.” While paying attention to this ideological aspect of the film and the centrality of science as a national developmental agenda in South Korea, the essay also looks closely at the anxieties behind the Cold War science within Yonggari, as the “silenced” nuclear disaster of Japan started to be publicly spoken in South Korean media in the mid-1960s. The film reminded Koreans of the victims in Hiroshima and Nagasaki and of East Asian “Hot Wars” that were hidden behind monstrous Cold War science.