Just as the international community is making inroads combating sexual violence as a weapon of war, extremists are using the tactic as a tool of terror.

Zainab Bangura, the United Nation's Special Representative on Sexual Violence in Conflict, said extremist groups use the promise of wives and sex slaves to attract recruits and compensate fighters. The sale of women also generates funds for terrorist groups much like oil, antiquities and drugs.

Bangura said that of the 48 parties accused of employing sexual violence in a new U.N. report 37 were non-state actors, requiring new tools and strategies to address the scourge.

She said that efforts should focus on draining extremists' resources and degrading their capacity to communicate, travel and do harm as well as providing better care to victims.