"Star Trek evoked this sense of technological insecurity when it introduced the Romulan Empire in the gripping "Balance of Terror." Unlike the expansionist Klingons, the Romulans are xenophobic and insular, destroying anyone who violates the Neutral Zone. Thus, the Romulan Empire resembled Mao's isolationist China, then in the grips of the Cultural Revolution — a closed society perceived as a potential threat that might at any moment pour across neighboring borders. The Romulan Neutral Zone also references the Demilitarized Zone separating the divided northern and southern halves of Korea and (at the time) Vietnam."