International law prohibits young people under the age of 18 taking part in armed conflict, and the use of children under the age of 15 is considered a war crime. The United Nations defines child soldiers as 'children associated with armed forces and groups' Not all children have armed roles in these groups, so referring to them as 'child soldiers' isn't always accurate as they may be used in any capacity - including as spies, messengers, porters, servants or for sexual purposes.