The United States' diplomatic mission in Somalia has directed all non-essential staff to leave the capital Mogadishu, saying it had received a "specific threat" against its employees.
The move came a day after Washington carried out its first air strikes against Islamic State militants in the country. It said the raids killed "several terrorists".
"Due to specific threat information against US personnel on the Mogadishu International Airport, the US mission to Somalia has directed its non-essential US citizen employees to depart Mogadishu until further notice," a statement said.
It did not give further details.
IS has been gathering recruits in the region but it remains a small player compared with the al Shabaab group.
Last month, a group loyal to IS seized a small port town in Somalia's semi-autonomous Puntland region.
Al Shabaab is linked to IS' rival al-Qaeda and once controlled much of Somalia.
The group aims to drive out international peacekeepers, topple Somalia's Western-backed government and impose its strict version of Islam on the Horn of Africa state.
