Somalia's al-Shabab extremist group attacked a military base used by US and Kenyan troops in coastal Kenya early Sunday, destroying US aircraft and vehicles, Kenyan authorities said.
Kenya's military said the pre-dawn assault was repulsed and at least four attackers were killed.
It was the first known al-Shabab attack against US forces inside Kenya, a key base for fighting one of the world's most resilient extremist organizations.
A plume of black smoke rose above the base near the border with Somalia, where al-Shabab is based.
Residents said a car bomb had exploded.
Lamu county commissioner Irungu Macharia told The Associated Press that five suspects were arrested and were being interrogated.
The US Africa Command confirmed the attack on Camp Simba in Lamu county.
Spokesman Col. Christopher Karns called al-Shabab's claims, including that its attack inflicted severe casualties, grossly exaggerated."
Kenya's military, however, said that the airstrip is safe."
It said that arising from the unsuccessful breach a fire broke out affecting some of the fuel tanks located at the airstrip."
But if Kenyan claims true, AS attack may have been well-timed to signal to Iran it is open for tactical alliances," he wrote, adding that an AS that forges relations with Iran is nightmare scenario."
When asked whether the US military was looking into any Iranian link to the attack, spokesman Karns said only that al-Shabab, affiliated with al-Qaida, has their own agenda and have made clear their desire to attack US interests."