Associate Fellow, International Law Programme, Chatham House
27 June 2019
• Although sieges may conjure up images of medieval warfare, they are still used by armed forces today, in international and non-international armed conflicts.
• International law does not define sieges, but their essence is the isolation of enemy forces from reinforcements and supplies. Sieges typically combine two elements: ‘encirclement’ of an area for the purpose of isolating it, and bombardment.
• Questions of the compatibility of sieges with modern rules of international humanitarian law (IHL) arise when besieged areas contain civilians as well as enemy forces.
• Sieges are not prohibited as such by either IHL or other areas of public international law.
• Three sets of rules of IHL are relevant to sieges. The first comprises the rules regulating the conduct of hostilities. The second is the prohibition of starvation of civilians as a method of warfare, along with the rules regulating humanitarian relief operations. The third comprises the rules on evacuation of civilians.
• The application of IHL to sieges is unsettled in some respects. This briefing does not purport to resolve all the difficulties or address all the issues in detail.
• While it may go too far to say that it is now impossible to conduct a siege that complies with IHL, the significant vulnerability of civilians caught up in sieges puts particular emphasis on the need for both besieging and besieged forces to comply scrupulously with the legal provisions for the protection of civilians and to conclude agreements for their evacuation.