The US has issued a travel warning for Kenya ahead of a visit by President Barack Obama, who is due to address a summit on global entrepreneurship.
The summit, to be held in the capital, Nairobi, from July 24-26, could provide “a target for terrorists”, the US State Department said in a statement.
In 2013, at least 67 people died in an attack by al-Shabaab militants on the Westgate shop centre in Nairobi.
The Somali-based Islamist militant group says it is at war with Kenya.
Their deadliest assault to date happened at a university in the North-Eastern Kenyan town of Garissa in April, when four gunmen killed 148 people.
The US State Department has urged its citizens to “maintain a high level of security awareness” as part of the new travel warning, which expires on July 30.
Last month, the UK lifted its warning against travelling to part of Kenya’s coast, including Mombasa.
Mr Obama’s visit to Kenya will be his first to his father’s homeland as US leader.
Al-Shabaab has carried out numerous attacks in Kenya near the long porous border with Somalia.
The al-Qaeda-linked group wants Kenya to withdraw troops sent to Somalia in 2011 to help the weak UN-backed Somali government to fight the militants.