Can the fatality of a terror attack determine the level of public support for violent retaliatory policies? Can this relationship indicate response proportionality? This replication and extension study examines the empirical linkages between exposure to non-fatal and fatal terrorism and support for violent retaliatory policies to determine whether response proportionality can be observed in public support for violent counterterrorism policies. Building upon the original study by Shandler et al. (2021), which employed a series of randomized controlled experiments to 1,848 participants across the United States, United Kingdom, and Israel to examine the political effects of exposure to cyberterrorism on support for retaliation, this study utilizes the data from these controlled experiments and employs a distinct set of statistical analyses to instead investigate response proportionality, exploring the association between terrorism attack fatality and public support for various violent retaliatory policies. Findings indicate that the level of public support for violent retaliatory responses is dependent on attack fatality, confirming the existence of response proportionality in public support for violent counterterrorism policies. This study found little evidence of response proportionality in public support for non-violent counterterrorism responses. Most critically, this study found that regardless of attack fatality, participants disapproved of retaliatory policies that result in adversary civilian harm, indicating that public counterterrorism opinions align with existing state and international norms of proportionality. As the consideration of both public support and proportionality are vital to state counterterrorism operations, this study extends to the realm of foreign policy the existence of a relationship between these two factors. While existing literature suggests public opinion favors disproportional retaliation responses, this study argues proportionality may influence public counterterrorism opinion more than research has previously established.