When do countries apologize for wartime crimes? Why do some refuse to apologize altogether? Apologies often serve as the vital first step to reconciliation between former wartime foes. Yet, to date, International Relations offers few answers as to when a country will issue a sincere apology to signal goodwill.

Drawing on the costly signalling literature in Economics and International Relations, I argue that when the recipient can credibly promise that it will not exploit the apology for further compensation in the future, the sender is more likely to give a stronger apology. I use the case of Japan to test my arguments, a former Axis Power that continues to apologize to multiple countries for war crimes committed during the Second World War.

To pin down the causal mechanism, I design a stylized randomized experiment among Japanese citizens, which will accompany case study research.