When the 4th Corps was subsequently organized in summer and fall 2015, forces of widely different origins were included: Among these were the 103rd Republican Guard Brigade which would serve as HQ for the new corps, along with troops drawn from the 3rd and 4th Divisions, as well as Ba'ath Party, NDF, and Alawite militias. The Alawite fighters were organized into 12 units which fought under the joint command of Russian, Syrian, and Iranian officers. The remained was grouped into four "volunteer brigades", while several smaller Russian units were assigned to it in a support role. Directly paid by the Republican Guard and the government, the 4th Corps was described by Carnegie Middle East Center's expert Kheder Khaddour a formation that "blends army and militia forces".