By 1997, seven groups in the government camp, led by former Garang lieutenant Riek Machar, signed the Khartoum Peace Agreement with the NIF, thereby forming the largely symbolic South Sudan Defence Forces (SSDF) umbrella. Furthermore, the government signed the Nuba Mountains, and Fashoda agreements with rebel factions. These included the Khartoum agreements that ended military conflict between the government and significant rebel factions. Many of those leaders then moved to Khartoum where they assumed marginal roles in the central government, or collaborated with the government in military engagements against the SPLA. These three agreements paralleled the terms and conditions of the IGAD agreement, calling for a degree of autonomy for the south and the right of self-determination. Nevertheless, the SPLA made major advances in 1997 due to the success of Operation Thunderbolt, an offensive during which the South Sudanese separatists seized most of Central and Western Equatoria from the government.