Mogadishu (AFP) - US military forces launched air strikes against the leader of Somalia's Al-Qaeda-linked Shebab, the government said Tuesday, claiming "casualties" but with no details if the main target was killed. "The Americans carried out a major air strike targeting a gathering by senior Al-Shebab officials, including their leader Abu-Zubayr," said Abdukadir Mohamed Nur, governor for southern Somalia's Lower Shabelle region.Abu-Zubayr is the often used name for Shebab supreme commander Ahmed Abdi Godane, listed by the US State Department as one of the world's eight top terror fugitives.The Pentagon have confirmed an "operation" was carried out."We are assessing the results of the operation and will provide additional information as and when appropriate," Pentagon Press Secretary Rear Admiral John Kirby said in a statement.The air strike on Monday comes days after African Union troops and government forces launched a fresh offensive against Shebab strongholds aimed at seizing key ports, and cutting off an important source of revenue for the Islamist rebels.Shebab fighters have largely fled in the face of the offensive that began Friday, and Nur said the air strike was targeting Shebab commanders as they gathered for a meeting."They were meeting to discuss about the current offensive in the region," Nur said.