The South Sudan People's Defence Forces (SSPDF), formerly the Sudan People's Liberation Army (SPLA), is the army of the Republic of South Sudan. The SPLA was founded as a guerrilla movement against the government of Sudan in 1983 and was a key participant of the Second Sudanese Civil War, led by John Garang. After Garang's death in 2005, Salva Kiir was named the SPLA's new Commander-in-Chief. As of 2010, the SPLA was divided into divisions of 10,000–14,000 soldiers.

Following the Comprehensive Peace Agreement in 2005, the last remaining large and well-equipped militia, the South Sudan Defence Forces (SSDF), under General Paulino Matiep, signed an agreement with Kiir known as the Juba Declaration, which amalgamated the two forces under the SPLA banner.

Following South Sudan's independence in 2011, Kiir became President and the SPLA became the new republic's regular army. In May 2017 there was a restructure and the SPLA took on the name of South Sudan Defence Forces (SSDF), with another change in September 2018 to South Sudan People's Defence Forces. As of 2018, the army was estimated to have 185,000 soldiers as well as an unknown number of personnel in the small South Sudan Air Force. As of 2019, the SSPDF comprised the Ground Force, Air Force, Air Defence Forces and Presidential Guard.