The United States Africa Command said the airstrike occurred near Jilib, a town not far from the East African coast, in the Middle Juba region. There were no reports of Americans killed or wounded.
The statement did not say whether any Somali forces were killed or wounded by the extremists, who are linked to Al Qaeda. The Shabab, via its Shahada news agency, asserted that its attack on two Somali army bases killed at least 41 soldiers. It described the location as the Bar Sanjuni area near the port city of Kismayo.
There was no immediate comment from Somalia’s government.
The Shabab controls large parts of rural southern and central Somalia and continues to carry out suicide bombings and other attacks in the capital, Mogadishu, and elsewhere.
The group had claimed responsibility this week for the deadly attack on a luxury hotel complex in Nairobi, the capital of neighboring Kenya, on Tuesday, the latest high-toll assault inside that county in retaliation for Kenya sending troops to Somalia to fight the Shabab. The attack killed at least 14 people.
In neighboring Ethiopia, state television cited the defense ministry as saying more than 60 Shabab fighters had been killed in the airstrike and that four vehicles loaded with explosives had been “destroyed.” Ethiopia contributes troops to a multinational African Union peacekeeping mission in Somalia and has troops there independently under the Ethiopian army’s command.
A Somali intelligence officer said the Shabab had been amassing fighters for more than a week to launch a major attack against Somali and Kenyan forces in order to disrupt a planned offensive against the extremists. The officer said some 400 militants, including foreign ones and suicide car bombers, had been prepared. The officer spoke on condition of anonymity because they were not authorized to speak to reporters.
The extremist group has found itself under pressure at home on a number of fronts, including from a small presence of rival fighters linked to the Islamic State, which has begun challenging the Shabab in recent months.
The United States has dramatically stepped up airstrikes against Shabab militants in Somalia since President Trump took office, carrying out at least 47 such strikes last year. Some have targeted top Shabab leaders or key financial officials; the extremist group funds its attacks with an extensive network of “taxation” and extortion.
In October, the United States said an airstrike killed about 60 fighters near the Shabab-controlled community of Harardere in the central Mudug Province.
The airstrikes hamper the extremist group but have not “seriously degraded al-Shabab’s capability to mount strikes either inside or outside Somalia,” Matt Bryden of Sahan Research, an expert on the extremists, told The Associated Press after the Nairobi hotel attack.
Airstrikes alone cannot defeat the militants, Mr. Bryden said, and must be combined with more ground-based attacks as well as a nonmilitary campaign to win over residents of extremist-held areas.
The United States on Saturday said it was committed to “preventing al-Shabab from taking advantage of safe havens from which they can build capacity and attack the people of Somalia.”