Blocking of humanitarian aid can result in several ways. It can be imposed on a region by foreign governments or non-state actors,[1][2] but it can also result from the lack of consent for assistance by the host nation.[3] Blocking of humanitarian aid to intentionally cause destruction of part or all of a population can amount to the crime against humanity of extermination.[4] If, however, the humanitarian aid (e.g., medical supplies, food, clothing) is systematically diverted for military use by enemy combatants during war, then allowing the passage of humanitarian aid is not required, as explained in Article 23 of the Fourth Geneva Convention.[5] There are different interpretations of how the requirement of proportionality should determine the extent to which a siege to block such aid can legally be carried out.[6]
Subjecting a large number of people to conditions of life that would inevitably lead to death could constitute extermination. This could take various forms, including the intentional deprivation of food or medicine, the denial or preventing of aid delivery, the creation of a humanitarian crisis, the forced performance of death-marches, or the denial of shelter in extreme circumstances. Such acts, like other forms of killing, would be subject to the requirement of scale discussed above to qualify as extermination. Where the accused is charged with creating or contributing to such conditions, it would have to be proved that he intended by his conduct to contribute to the death of the victims.
In addition, it also grants the States concerned the right to inspect the contents and verify the destination of relief supplies, as well as to refuse the passage of relief goods if they have well-founded reasons to believe that they will not be distributed to the victims but rather used in the military effort.
Of course, the devil of the starvation rule is in its details and interpretation. Frankly, it's unclear how the imposed deprivations at the heart of siege fare under this rule. By one interpretation, the rule prohibits any starvation of civilians, including as an incidental effect of an effort to starve defending forces into submission. But another interpretation maintains that only starvation directed specifically at civilians is prohibited. By this view incidental though foreseeable effects of civilian starvation are not prohibited, although they must not be disproportionate, that is, excessive in relation to anticipated military advantage. Although this latter view is held by the United States (§. 5.20), it reduces the rule's humanitarian effect, perhaps to the vanishing point.
