Cairo - Al-Qaeda's leader is urging Muslims to join militants in Somalia in the battle against African Union troops, which he says have been boosted by US support.
Ayman Al-Zawahri says Somalia's al-Qaeda branch, al-Shabaab, should use guerrilla tactics and suicide bombings to wage jihad, or holy war.
Somalia had been in chaos for years, ruled by warlords and insurgents bent on creating an Islamic state.
The militants, who once controlled nearly all of Mogadishu, have been gone from the capital for more than a year, and in September the African troops booted them out of their last urban stronghold, the port city of Kismayo.
In his seven-minute audio message posted late on Tuesday on militant websites, al-Zawahri says the loss of Kismayo came after "clear, direct and flagrant support from the Americans."