There has been much speculation about foreign involvement in facilitating the creation of the AFDL. Most of it swirls around Rwandan President Paul Kagame and Ugandan President Yoweri Museveni, both of whom knew Kabila very well. (Kabila had been introduced to Kagame and Museveni by Mwalimu Julius Nyerere, president of Tanzania). After an initial period of denial, since 1997 both Rwanda and Uganda have openly acknowledged the role they played in the formation of the AFDL and its military success. Rwanda and Uganda quickly threw the weight of their support behind the AFDL and sent forces across the Zairian border. Burundi, Angola, the rebels of southern Sudan, and the security forces of the province of Katanga, all of which had long-standing grievances with the Mobutu government, especially his sponsoring of foreign rebel groups to destabilize neighboring countries, also proved to be important backers of the AFDL.