The spectre of a foreign enemy has been al-Shabaab's most effective recruiting tool over the last three years. The presence of an occupying force from Ethiopia enabled militant leaders to cast the fighting as a holy war and in the process drive out a far larger force.

Now the stepped-up US presence is helping the rebels to rally support as they dismiss the transitional government in Mogadishu as a foreign puppet. Large-scale defections to the militants have sapped the strength of government forces and placed US weapons in the hands of al-Shabaab, according to Somali sources.

Last month in Nairobi, the US Secretary of State, Hillary Clinton, said Washington would support the "moderate" Islamist Sheikh Sharif Sheikh Ahmed in his fight against the insurgents but said it would limit itself to supplying arms and funding.

Now that claim appears suspect.

One of the first groups to welcome the US strike against suspected al- Qa'ida terrorist Saleh Ali Saleh Nabhan was the Somali militia Ahlu Sunna, loyal to the transitional government. The overt taking of sides, reminiscent of Iraq and Afghanistan, risks turning the African civil war into a magnet for global jihadists – something Washington says it's aiming to prevent.

A former USAID analyst who has worked on both Afghan and Somali issues says the clearest parallels between the crises lie in the mistakes that are being made.

"US strategy has been to say that since nobody's hands are clean, you pick sides. Pick a few warlords, pay them off and then offer them impunity whatever they do."

The analyst, who cannot be named, said the confusion has been there since 2006 when the US was paying for aid programmes in the same places where it was launching air strikes.

"The US was bombing the same areas it was paying millions in aid through the UN to on the same day. It was ridiculous," the analyst said.

Continued mishandling of the Horn of Africa crisis also risks making the warnings of a radicalised Somali diaspora turning on their host countries into a reality.