Separate attacks have targeted a US military base in the Somali town of Baledogle and a European military convoy in the capital, Mogadishu.
A bomb attack was followed by small arms fire at a base operated by US special forces on Monday, a security source told Reuters news agency.
The Somali armed group al-Shabab claimed responsibility for the attack at the Balidogle base located in the Lower Shabelle region, about 100km (60 miles) west of Mogadishu.
Italy’s defence ministry in a statement confirmed that an Italian military convoy was hit by an explosion. No injuries had been reported so far, the defence ministry said.
Al Jazeera’s Malcom Webb, reporting from neighbouring Kenya, said the first attack targeted the base, housing US troops and Somali soldiers,