Existing research emphasizes how United Nations Security Council (UNSC) approval helps convey information to domestic audiences that military action is conducted with good intentions, for desirable consequences and in a legitimate manner. This information transmission mechanism can also increase support for UNSC-endorsed military action in countries unlikely to provide major contributions to military actions. There is some cross-national evidence supporting the information transmission mechanism in the United States. Examining the causal mechanisms underlying foreign public support for US military action through a survey experiment with approximately 2,000 respondents in Japan shows that foreign public support varies depending on whether the military action has UNSC approval. The process of presenting draft resolutions to the UNSC also affects public support.