The South Sudan Democratic Movement (SSDM), sometimes called the South Sudan Democratic Movement/Army (SSDM/A), is a South Sudanese militant group. Along with its armed wing, the South Sudan Defence Army (SSDA), it is currently in rebellion against the government of South Sudan led by President Salva Kiir Mayardit and the Sudan People's Liberation Movement.
The Movement, which was formed in 2010 by controversial former Sudan People's Liberation Army general George Athor after he failed to win the governorship of Jonglei in what was then the Autonomous Government of Southern Sudan, is active in the state of Jonglei as well as neighbouring Upper Nile in the Republic of South Sudan. Many SSDM fighters are from the Murle, a minority tribe that has long disputed herds of livestock and pasturing grounds with a fellow cattle ranching tribe, the Lou Nuer. Under Athor's leadership, Murle tribesmen repeatedly clashed with the Lou Nuer and the armed forces of South Sudan throughout much of 2011.
The Sudan People's Liberation Army (SPLA) has accused the North Sudanese government of supporting the SSDM, though SPLA officials have not elaborated on what role they believe Khartoum's backing has played.