Self-inflicted

Via BBC:

So with tacit American approval and with other international governments looking on, Ethiopia sent troops into Somalia to support the weak transitional government.

Ethiopia is now trapped.

It wants to get out of Somalia, but cannot go until what it calls the "Islamist threat" is eliminated.

But every moment Ethiopian troops spend in Somalia stirs up more resentment and their presence acts as a compelling recruiting sergeant for insurgents, who say they will die trying to rid their country of the Ethiopian invaders.