Abstract: Why do some individuals with military experience support the insurrection of January 6? With US military veterans playing a central role in the assault on the US Capitol, answering this question is of immediate scholarly and policy concern. To better understand the impact of military service, we conducted the first nationally representative survey of support for pro-Trump anti-democratic violence ("insurrectionist sentiments") among US military veterans and a demographically matched sample of non-veterans. Our analysis finds veterans nearly twice as likely to hold high insurrectionist sentiments than non-veterans, and that military service increases support for restoring Trump to the presidency by force by 15 percent. Further, we find the effect veterancy is not fully explained by veterans being more likely to hold pro-Trump or conspiracy beliefs but is associated with negative military and post-service-related experiences. These findings are robust to significant unobserved confounding. We conclude with implications for future research on political violence and the role of the military in American democracy.