The completion of the formalities for the opening of a third African Sub-Regional Bureau - in Kenya, for Eastern Africa - resulted in the formal agreement between Interpol and the Republic of Kenya, on which its operation is based, coming into force in September 1999. The other two Sub-Regional Bureaux in Africa - in Abidjan and Harare - serve West & Central Africa and Southern Africa. These three offices are integral components of regional structures established within their respective geographical zones to ensure close international co-operation to tackle crime.