The UN Security Council adopted a resolution Tuesday to increase the UN-backed African Union peacekeeping force in Somalia by more than 4,000. The resolution will increase the number of troops of the African Union Mission in Somalia (AMISOM) to a maximum of 22,126 from its current level of 17,731 and extended its mandate until October 31, 2014. The increase is aimed at strengthening Somali and AMISOM troops in their efforts against al-Shabaab, an al-Qaeda-affiliated group. The Security Council decided that the increase in the force strength should "provide short-term enhancement of AMISOM's military capacity for a period of 18 to 24 months and as part of an overall strategy for AMISOM," the resolution read, dpa reported.