The dire humanitarian situation and the staggering death toll associated with sieges in recent conflicts call for an urgent revisiting of how such instances are regulated by international humanitarian law (IHL). This chapter focuses on conduct of hostilities (CoH) rules and adopts the view that the isolation aspect of sieges qualifies per se as an attack, in view of the violent consequences that ensue and irrespective of additional acts of violence that may be directed against targets within the area under siege. Further, it argues that when civilians are trapped in besieged areas, such attacks likely violate the principle of distinction and are, thus, prohibited as indiscriminate. The chapter then examines whether the adoption of specific precautionary measures, including facilitating the rapid and unimpeded passage of humanitarian relief schemes in besieged areas and allowing civilians to leave such areas, rules out the indiscriminate character of a siege. Additionally, it explores under what circumstances a siege that amounts to an indiscriminate attack can result in individual criminal responsibility under the Rome Statute of the International Criminal Court (ICC) and whether a siege can potentially coexist with an occupation and, if so, respect the law of occupation.