GANGNEUNG, South Korea—A dramatic synthesizer crescendo kicked off an unusual show in this Olympic host city on Thursday: It was a North Korean propaganda orchestra, performing for a packed house of South Korean spectators eager for a glimpse of the other side.

The Samjiyon Orchestra began its 90-minute performance at the Gangneung Arts Center with the upbeat North Korean pop song “Glad to See You,” a catchy tune that has become familiar to some South Koreans over the years. The song was greeted with thunderous applause.​

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