Throughout history, sieges of cities and densely populated areas have played a key role in military operations. Despite its prevalence as a method of warfare, the Law of Armed Conflict does not provide a definition of siege, nor does it determine whether it constitutes a lawful method of warfare or qualifies as an attack. Within this legal framework, tension arises between the military advantages of sieges and humanitarian considerations when civilians are present in the besieged area. In this sense, this thesis seeks to ascertain in which manner should the principle of proportionality be applied to sieges.