Separate attacks hit a U.S. military base in the Somali town of Baledogle and a European military convoy in the Somali capital on Monday, a Reuters witness and a security source said.
A Reuters journalist saw a seriously damaged armoured vehicle bearing a small Italian flag sticker in the capital of Mogadishu. It was unclear if there were any casualties.
Italy's defence ministry said in a statement that an Italian military convoy had been hit by an explosion. No injuries had been reported so far, the defence ministry said.
Also on Monday morning, there was a bomb attack followed by small arms fire at a base operated by U.S. special forces, a security source told Reuters.
The insurgent group al Shabaab claimed responsibility for the attack.
"In the early hours of Monday morning, an elite unit of soldiers from Harakat Al-Shabaab Al Mujahideen's Martyrdom Brigade launched a daring raid on the U.S. military base," the group's press release said.
"After breaching the perimeters of the heavily fortified base, the mujahideen (holy warriors) stormed the military complex, engaging the crusaders in an intense firefight."
The Balidogle base is in the Lower Shabelle region, about 100 km (60 miles) west of the capital Mogadishu.