The role of public attitudes toward war in shaping foreign policy is crucial. We explored the association between perceived justifiability of Russia’s actions, attitudes toward Israel’s policy during the Russia-Ukraine War, and emotional reactions among the Israeli lay public. A cross-sectional study was conducted among 723 participants during one week of the war (13-20 March 2022). Participants completed measures of emotional reactions, perceived justifiability, attitudes toward Israel’s policy, and socio-demographics. Emotional reactions were relatively high, perceived justifiability low, and supportive attitudes toward Israel’s policy were moderate. Higher emotional reactions were noted among females, older participants, and those not born in Israel, along with lower perceived justifiability and greater support for Israel’s policy. Attitudes significantly mediated the relationship between perceived justifiability and emotional reactions. Although the Israeli public is not directly involved, the war has elicited emotional reactions in them. Addressing these negative emotional responses is essential in informing Israel’s policymaking.