A US special forces soldier was killed in an attack by suspected al-Shabab militants in southwestern Somalia, officials said.
Four other US soldiers and a Somali soldier were wounded in what appears to have been an ambush near the town of Jamaame, US defense officials said.
US forces were operating alongside Somali troops.
It was the first known American death in combat in Africa since an ambush in Niger in October, the New York Times reported.
The militants launched the attack using small arms and mortar fire against a small outpost, defense officials quoted by the Times said.
The United States Army says that its forces operate in a “advise and assist” mission with the Somali national army.
Traditionally, US presidents have been wary of intervening in Somalia since 18 special forces soldiers died fighting militias in Mogadishu in 1993, a dramatized battle in the movie Black Hawk Down.
However, President Donald Trump has expanded military operations against al-Shabab, the al-Qaeda affiliate there.
Al-Shabab was expelled from the capital, Mogadishu, in August 2011 after an offensive led by troops of the African Union (AU), and left the vital port of Kismayo in September 2012.
However, it still has a strong presence in the regions of the capital.