In March 1989 soldiers of the Ogadeni clan mutinied in Kismayo (Chisimaio), and fighting continued until the government troops gained the upper hand in July.
In particular, the Ogaden clan, living in both Somalia and Ethiopia and strongly interested in pan-Somali issues, tended to blame Siad Barre for Somalia's defeat in the 1977-78 Ogaden War. This suppressed resentment turned to defiant opposition after Siad Barre decided in 1988 to conclude a peace agreement with Ethiopia. The deteriorating relations between Siad Barre and former Ogaden supporters climaxed in 1990 with a mass desertion of Ogaden officers from the army. These officers allied with the Somali Patriotic Movement (SPM), a group that had formed in 1985 as a result of a split within the SSDF. The greatly enhanced military strength of the SPM enabled it to capture and hold several government garrisons in the south...
The SPM emerged in March 1989, after a group of Ogaden officers, led by Umar Jess, deserted the SNA and took up arms against Siad Barre. Like the USC, the SPM experienced a division among its ranks. The moderates, under Jess, favored an alliance with the SNM and USC and believed that Somalia should abandon its claims to the Ogaden. SPM hardliners wanted to recapture the Ogaden and favored a stronger military presence along the Somali-Ethiopian border.