A US Department of Defense (DoD) representative confirmed to AFP that one American soldier was killed and four were wounded.
The attack by suspected Al-Shabaab militants occurred on Friday in Somalia's southern Jubaland province, where a small joint US-Somali outpost came under small arms and mortar fire, US defense officials said.
Friday's joint operation involved both Somali and Kenyan militaries, with the US providing assistance and surveillance during the operation.
We also injured four USA soldiers, ' Abdiasis Abu Musab, al Shabaab's military operations spokesman said.
An American service member was killed in Somalia Friday and four others were wounded in a firefight with Al Shabab fighters, according to U.S. Africa Command (Africom). The operation aimed to clear the Somalia-based extremist group al-Shabab from contested areas.
Al Jazeera's Rosiland Jordan, reporting from Washington, DC, said about 500 United States troops are deployed in Somalia, including highly-trained special forces and Navy Seals.
The al-Qaida-linked al-Shabaab rural south and central regions, claimed responsibility.
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Friday's incident marked the first time a USA service member has died in action in Somalia since Navy SEAL Kyle Milliken, a senior chief petty officer, was killed in May of a year ago in a firefight with al-Shabab militants.
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.
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.
The U.S. team was backed up by armed surveillance aircraft, the officials said.
Names are being withheld pending next-of-kin notification, officials said in a statement, adding that the command's thoughts and prayers are with the families and friends of the service members. Al-Shabaab is an al-Qaeda affiliate operating to overthrow the Somalian government, and it took credit for the attack.
More than 7,300 Special Operations troops are working around the world, many of them conducting shadow wars against terrorists in Yemen, Libya, Somalia and other hot spots.
Al-Shabab was forced out of the capital, Mogadishu, in August 2011 following an offensive spearheaded by African Union (AU) troops, and left the vital port of Kismayo in September 2012.