We present an innovative approach to quickly estimate collateral damage based on the given weapon-target assignment (WTA). That is, having the predetermined WTA, we estimate the collateral damage of friendly or neutral entities based on the lethality of engaging weapons and the geo-locations of all the entities in the theater. Specifically, we calculate the probability of killing/destroying k friendly (or neutral) assets for given k. The main motivation of this paper is twofold. First, quick collateral damage estimation (QCDE) can support commanders in the battlefields with a new quick decision-making capability. Second, our QCDE could support WTA capabilities with collateral damage consideration. Our computational results indicate that the error in estimating collateral damage is significantly less than 1% and that the execution times are of the order of milliseconds for k (k <;9) assets. Hence, the natural research challenge related to this paper would be the extension of our quick collateral damage estimation to k ≥ 9 that would execute in reasonable time and give a reasonable quality solution.