- Special Representative of the UN Secretary-General for West Africa and the Sahel (2014-2021)
- Head of UNOWAS, the UN Office for West Africa and the Sahel (2014-2021)
- President of ECOWAS, the Economic Community of West African States (2002-2006)
- Ghana’s Deputy Foreign Secretary (1987) and Deputy Minister of Education (1997-2000)
- Mediator in the first Liberian civil war in the 1990s and the Ivorian civil war in the early 2000s