Just went through some really fascinating MID reports related to the bombing of Chinchow (Jinzhou) in October, 1931. 11 Japanese aircraft dropped some bombs in the vicinity of the city. There were civilian casualties. The Japanese released their own version of events.
The Americans weren't happy, evidently. The Secretary of State ordered an investigation, which was quite extensive. It included eyewitness testimony, photographs, and documentary evidence. The 2nd image includes a light-hearted comment from one eyewitness of the events.
Included is a translation of the leaflets dropped by the Japanese. I think the 2nd image is a copy of an original? The report isn't clear. Anyone with the language skills can feel free to correct me. "In order to eradicate this evil, our army is adopting a self-defense action."