On August 6, 2011, Al-Shabaab was forced to withdraw from most of Mogadishu. Al-Shabaab did still retain a foothold in the northern outskirts of the capital, but by January 2012, the combined efforts of Somali government and AMISOM forces had expelled them from the city completely. An ideological rift within Al-Shabaab's leadership also emerged after the 2011 drought and the assassination of top officials in the organization. With the majority of Mogadishu secure, the Somali Armed Forces and Kenya Defence Forces next launched Operation Linda Nchi, a joint advance against Al-Shabaab, in October 2011. This operation had reportedly been planned for nearly two years, during which time Kenyan officials sought U.S. support for the mission. After the successful conclusion of Operation Linda Nchi in May 2012, Kenyan troops were formally integrated into AMISOM in June. After Operation Linda Nchi, the port city of Kismayo was the last major stronghold that remained in Al-Shabaab's control. A Kenyan-led AMISOM force, backed by the Raskamboni movement, then launched an offensive against Kismayo on September 28, 2012. After a three-day battle, Somali government forces were able to gain control of the city. The month of September 2012 also saw the establishment of the Federal Government of Somalia.