The overnight incursion into the strategically important town of Belet Weyne is the first time Ethiopian troops have seized control of a town in war-ravaged Somalia since leaving the country in January as part of a peace deal. The Islamist insurgency had used the presence of Ethiopian Christian troops on Somali soil as a propaganda tool to recruit fighters.
Local resident Abdinur Ahmed Maow said the Ethiopians who crossed the border joined other Ethiopian troops had been near the town for around three days and that the Islamist forces left "without a single shot."
Islamist fighters had been present in the western part of the town, which is divided by a river, since the Ethiopian pullout in January.
Resident Abdulahi Faramiliq said the troops were cordoning off residential areas and going house-to-house searching for weapons.
Kenya-based Somalia analyst Rashid Abdi at the International Crisis Group, a conflict-resolution organization, said it was unlikely the troops were a vanguard for a larger Ethiopian force.
"It's a strategic town for them," he said, referring to the town's location near the border. "They want a buffer zone and they won't allow it to be in hostile hands."
There have been several reports of Ethiopian troops crossing the border in recent months but the Somali government has not publicized their presence. Ethiopian soldiers are unpopular with the majority of Somalis, both because they are often Christian and because human rights groups say they committed a string of rights abuses during their two-year occupation of the country. The Somali government military commander in the region, General Muqtar Hassan Afrah, denied the Ethiopians were in town and said only Somali troops were in Belet Weyne.