The aim of this paper is twofold. First, we argue that killing a Conditional Threat usually involves an unnecessary act of self-defense, so killing this aggressor is usually morally impermissible. We defend this thesis by showing that this case is fundamentally similar to a case involving an Unconditional Threat in which the victim can flee to safety although this involves incurring a minor cost. Second, we analyze the thresholds of maximal harm that victims are required to bear before they are (...) permitted to defend themselves by harming their aggressors related to the conditions of necessity and of proportionality. We argue that the maximal harm a victim is required to bear sanctioned by the condition of necessity is, all else being equal, lower than the maximal harm that a victim must bear sanctioned by the condition of proportionality. This result is relevant for determining in which cases victims may use lethal force against Conditional Threats, both in the individual case and also in the case of war. (shrink)