The Law of Armed Conflict traditionally regulates the actions of States and armed groups, as well as individuals who participate in hostilities. It is increasingly evident that there are significant legal issues regarding the application of this law to the activities of International Military Missions, especially with regard to United Nations forces and other international organisations because it is unclear how their activities are regulated by traditional sources of International Law. The book explores the legal developments in addressing this challenge, including pertinent issues of human rights and international criminal law, elucidating the rights and obligations of all the actors, including States, international organisations and individuals, involved in International Military Missions.