Guerillas have vowed to retaliate after US special forces commandos swooped on a Somali village and killed two men, including a Kenyan national who Washington claims is one of Africa's most wanted terror suspects.
Somali witnesses to the raid on September 14 said that six helicopters buzzed Roobow village before two of the aircraft opened fire on a vehicle, killing two and wounding two.
US military officials said that forces from the US Joint Special Operations Command were involved in the raid, but refused to divulge details.
The deputy mayor for security affairs in Mogadishu, citing intelligence reports, claimed Kenyan citizen Saleh Ali Saleh Nabhan had been killed but did not elaborate.
Mr Nabhan was wanted for questioning in connection with the car bombing of an Israeli-owned beach resort in Kenya and a near-simultaneous attempt to shoot down an Israeli airliner in 2002.
Sheikh Bare Mohamed Farah Khoje, a spokesman for the al-Shabab militia that controls most of southern Somalia, said: "Muslims will retaliate against this unprovoked attack - we will never forget our brothers who were targeted illegally by the US.
"The US is Islam's known enemy and we will never expect mercy from them, nor should they expect mercy from us," he declared, vowing that Washington would "taste the bitterness of our response."
Another Islamist group linked to al-Shabab also expressed its outrage and predicted that the raid would feed local resentment.
Amal Islam chairman Sheikh Mohamed Ibrahim Bilal said: "This will only increase Somalis' hatred for the US, which never abides by international law in its war on Islam."