Nearly two-thirds of States are now party to the Optional Protocol to the UNCRC on the Involvement of Children in Armed Conflict. This Protocol, which came into force in 2002, establishes 18 as the minimum age for compulsory recruitment into armed forces and requires States to do everything they can to prevent individuals under the age of 18 from taking a direct part in hostilities.
These overarching protective mechanisms have been supplemented with many policies that have helped guide governments and international aid agencies. For example, rape and other forms of sexual violence constitute a war crime, or a crime against humanity, if committed as part of a widespread and systemic attack against a civilian population under the Rome Statute of the International Criminal Court. The Court also prohibits the use of children under 15 years old in hostilities and provides for its punishment as a war crime.