Killing in Combat as a Potentially Morally Injurious Event: The Diverging Psychological Impact of Killing on Peacekeepers and Combat-Oriented Troops

The impact of killing in combat (KIC) on veterans’ long-term psychological health is multifaceted and influenced by deployment contexts. This study compared two samples of Norwegian veterans from combat-oriented (Afghanistan 2001–2011, N = 4,053) and peacekeeping (Lebanon 1978–1998, N = 10,605) missions to examine how personal threats, witnessing death/injury, and KIC uniquely predicted long-term mental health, alcohol use, and quality of life (QoL). In the combat-oriented sample, personal threats and witnessing death/injury predicted negative outcomes, while KIC did not. Among peacekeepers, personal threats, witnessing death/injury, and KIC independently predicted posttraumatic stress disorder (PTSD), depression, anxiety, alcohol use, insomnia, and lower QoL. These findings reveal diverging effects of KIC on veterans from combat-oriented and peacekeeping missions, respectively, suggesting that the impact of potentially morally injurious events like KIC is shaped by mission-specific contextual factors.