A military operation is about to take place during an ongoing international armed conflict; it can be carried out either by aerial attack, which is expected to cause the deaths of enemy civilians, or by using ground troops, which is expected to cause the deaths of fewer enemy civilians but is expected to result in more deaths of compatriot soldiers. Does the principle of proportionality in international humanitarian law impose a duty on an attacker to expose its soldiers to life-threatening risks in order to minimise or avert risks of incidental damage to enemy civilians? If such a duty exists, is it absolute or qualified? And if it is a qualified duty, what considerations may be taken into account in determining its character and scope?

This article presents an analytic framework under the current international humanitarian law (IHL) legal structure, following a proportionality analysis. The proposed framework identifies five main positions for addressing the above queries. The five positions are arranged along two ‘axes’: a value ‘axis’, which identifies the value assigned to the lives of compatriot soldiers in relation to lives of enemy civilians; and a justification ‘axis’, which outlines the justificatory bases for assigning certain values to lives of compatriot soldiers and enemy civilians: intrinsic, instrumental or a combination thereof. The article critically assesses these positions, and favours a position which attributes a value to compatriot soldiers' lives, premised on a justificatory basis which marries intrinsic considerations with circumscribed instrumental considerations, avoiding the indeterminacy and normative questionability entailed by more expansive instrumental considerations.

In the future, it is likely that many battles will be fought in an urban environment. In such battles, the risk to both the civilian population and to attacking soldiers will be drastically increased. As a result, commanders will certainly face the very difficult dilemma of determining the amount of danger to which they will expose their forces in order to limit civilian casualties. Additionally, both strategic and tactical considerations will continue to play an influential role in determining their course of conduct on the battlefield.

This article seeks to explore these two issues, from the perspective of the rule of proportionality. It concludes that the current law of armed conflict does not explicitly require a commander to risk her soldiers' lives in order to reduce civilian casualties. However, there are moral reasons to accept such an obligation in certain situation, and this obligation might be embedded in the law of armed conflict through interpretation of current provisions or through the Martens Clause. Additionally the article concludes that while conducting the proportionality balancing test, a commander may consider the cumulative impact of both the tactical aspects of the operation and the strategic aspects of the overall operational plan or war strategy.