Conflicts in Ukraine and Africa are seeing more involvement of privately-run military groups.
Mercenaries or soldiers for hire are illegal in many countries.
A United Nations convention against their use has been ratified by more than 40 countries.
But big military powers including the United States, Russia, China, France and the United Kingdom are not party to that agreement – and some have used them extensively.
The Russian Wagner Group is involved in intense fighting in eastern Ukraine.
Previously, the former Blackwater security firm backed US forces in the 2003 war in Iraq.
Both organisations have been accused of human rights abuses.
So, why are some states increasing the use of mercenary forces? And who’s accountable for their actions?
Presenter: Folly Bah Thibault
Guests: Sorcha MacLeod – Chair of the United Nations Working Group on the Use of Mercenaries. Samuel Ramani – Associate fellow at the Royal United Services Institute and author of 'Putin’s War on Ukraine.' Marieke De Hoon – Assistant Professor in international criminal law at the University of Amsterdam and a specialist on crimes of aggression.
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