It was the first public announcement of a us military combat death on the African continent since four USA service members were killed in a militant ambush in Niger in October. Afterward, Africa Command revisited the protection that US troops in Africa on operations.
Friday's attack also follows the October 4 ambush in Niger that killed four American soldiers, their interpreter, and four Nigerien troops. A fourth servicemember suffered injuries minor enough to receive sufficient medical care in the field, AFRICOM said.
Details of the incident were first reported by the New York Times, which said American forces came under small arms and mortar fire while operating alongside Somali troops at a small outpost in the southwestern part of the country.
A Kenyan soldier working with the Somali forces being advised by the U.S. team was also wounded in the attack, according to three United States military officials.More news: Gary Rowett opens door for Xherdan Shaqiri exit
About 500 USA troops are deployed in Somalia.
The military did not say how many US personnel were part of the operation.
AFRICOM is withholding the name of the servicemember killed in action, pending notification of next of kin.
The U.S. had pulled out of the Horn of Africa nation after 1993, when two helicopters were shot down in Mogadishu and bodies of Americans were dragged through the streets.
President Donald J. Trump issued his condolences to the American soldier who lost his life on Friday. Al-Shabab has been blamed for the October truck bombing in Mogadishu that killed more than 500 people.More news: Buffett, Dimon and Bezos have a CEO for their health care venture
"My thoughts and prayers are with the families of our serviceman who was killed and his fellow servicemen who were wounded in Somolia".
The mission's objectives were to "clear Shabaab from contested areas, liberate villages from Shabaab control and establish a permanent combat outpost created to increase the span of federal government of Somalia security and governance", Africa Command said.
The group used to control most parts of the country, but since 2010, its fighters have been removed from most major towns and cities.
Late previous year USA drone strikes also began targeting a small presence of fighters linked to the Islamic State group in Somalia's north.More news: More Google Pixel 3 XL images leak, confirm all-glass back