The United States has ordered all non-essential employees of its mission to Somalia to leave the capital, Mogadishu, because of "specific threat information" against them.
Saturday's statement says the information relates to Mogadishu International Airport.
Somalia remains one of the world's most dangerous countries. The US hasn't had an embassy there since 1991 and calls security "extremely unstable."
Somalia's capital was rocked last month by the country's worst attack, which killed more than 350 people.
The US on Friday carried out its first airstrikes against ISIS fighters in Somalia.
The US Mission to Somalia is based in neighbouring Kenya. The first US ambassador to Somalia in a quarter-century told Radio Muqdisho in June that offices for a permanent diplomatic presence were expected to open in Mogadishu this year. (AFP)