US President Barack Obama said Saturday that Somalia's Al-Qaeda-linked Shebab militants had been "weakened," but that the overall security threat posed by the group remained.

"We have systematically reduced the territory that Al-Shebab controls. We have been able to decrease their effective control within Somalia and have weakened those networks operating here in East Africa. That doesn't mean the problem is solved," Obama said during a joint news conference with Kenyan President Uhuru Kenyatta.

"We can degrade significantly the capacity of the terrorist organisations, but they can still do damage," Obama said.