Abstract The effectiveness of public diplomacy is now increasingly the subject of scientific measurement and testing by researchers in the field of International Relations. While there are variety of empirical efforts to uncover the power of public diplomacy, extant studies have mostly focused on the activities initiated by the ministries in charge of external relations. In this article, rather than external relations ministries and agencies, we focus on the effectiveness of public diplomacy by the military. Specifically, we argue that figures, pictures and indeed videos created by military forces have power in changing perceptions among the receivers of the information. In this particular study, we show that a 38 second video made by the US military induces positive feelings for cooperation which would otherwise be difficult to sustain between South Korea and Japan — two countries which have suffered highly fractious relations, yet which are indispensable allies to the US in countering the rising threat from North Korea.