Because the underdog in a conflict typically gains the support of observers, nations will often adopt a narrative that persuades both their domestic following and international allies that they are the true victim in the conflict. Three survey studies were conducted to assess the perceptions of citizens of a third-party observer nation (Canada) in relation to two nations in conflict that differ in their historical persecution, namely the U.S. and Israel. Perceptions of the vulnerability of their safety and survival, and their strength to protect themselves against their opponents were hypothesized to mediate differences in the perceived justification for each nation's conflict actions. Study 1 (N = 91) supported this mediational model, with the U.S. seen as less vulnerable and more powerful than Israel, and perceptions of vulnerability accounting for differences in the justifiability of their respective conflict actions. Study 2 (N = 315) further demonstrated a moderating effect of Canadians' shared identity with the nations in conflict; only at lower levels of a shared identity was Israel perceived to be more vulnerable and the mediated relation with the perceived justifiability of its conflict actions retained. Study 3 was conducted 10 years later (2018), administering measures to an independent sample of Canadian participants (N = 300). Canadians were found to be significantly less likely to share a common identity with Americans than previously; once again, the mediating role of the perceived vulnerability of the nations in conflict and the justifiability of their actions was conditional on shared identification. The findings contribute to understanding influences on the credibility of victim claims by nations in conflict, as well as implications for how their actions are construed by citizens of a third-party observer nation.