Does war deepen gender inequalities in politicians’ behavior or help erase them? We draw from the terror management theory developed in psychology to argue that the onset of a violent conflict is likely to push politicians to conform more strongly with traditional gender stereotypes because it helps individuals cope with existential fears. To test our argument, we use data on Ukrainian politicians’ engagement on social media (136,455 Facebook posts by 469 politicians) in the three months before and after the 2022 Russian invasion of Ukraine, and interrupted time series analysis, to assess the effect of conflict on politicians’ behavior. We find that conflict onset deepens gender-stereotypical behavior among politicians in their public engagement. We also show that, consistent with our argument, gender biases among the public are magnified during war.