On April 27, 2017, the Governor of the Aden, Aidarus al-Zoubaidi, was fired by President Abdrabbuh Mansur Hadi for disloyalty to him, and for loyalty to the Southern Movement. On May 4, major rallies were held in Aden to protest President Hadi's decision. The STC was formed on May 11, 2017. One day later, Hadi called the council illegitimate.
Territorial situation in Yemen
Controlled by Southern Transitional Council
Beginning on 28 January 2018, separatists loyal to the STC seized control of the Yemeni government headquarters in Aden in a coup d'etat against the Hadi-led government.
President of the STC Aidarus al-Zoubaidi announced the state of emergency in Aden and that "the STC has begun the process of overthrowing Hadi’s rule over the South".
Mustafa Akhwand of Shia Rights Watch claimed that the battle was a dispute between Saudi Arabia and the UAE over the control of Yemen's newfound natural resources of oil, silver and gold discovered near the border with Oman. He also said that Hadi should resign and allow a more moderate candidate willing to cooperate with Houthis to become president in order to rebuild the country.
The STC took control of Aden, southern Yemen's main city, following the Battle of Aden (2018).
The STC is supported by the United Arab Emirates. According to Al-Jazeera, the "UAE has been financing and training armed groups in the south who answer to the STC's leader Zubaidi".
By late 2018, the STC had consolidated itself in the South. Its representatives were openly calling for a referendum for Southern indepedence; outside experts considered it likely that the majority of southern Yemen's population was by then supporting the southern separatists and their aims.
However, the military strength of the group is unclear. Although the STC holds shared interests and alliances with various armed groups, including the Southern Resistance (of which Zoubaidi is a commander), Adnan al-Kaf stated that multiple units including the Security Belts in Aden and Lahij, as well as Shabwani and Hadrami Elite Forces are not linked to the STC. Further, in June 2018 commander of the Brigade of Giants, Abu Zahra al-Mahrami, issued a statement refuting links between his brigade and the STC.