ADEN - Warships shelled suspected al Qaida strongholds in a mountainous region of southern Yemen on Thursday, in what two Yemeni government officials said they believed was a US operation.US officials could not be immediately reached for confirmation. The strikes come less than a week after a covert US Navy SEAL raid, also in Yemen's south, the first ordered by US President Donald Trump as commander in chief.The naval attacks appear to be part of an intensifying campaign against one of the most active branches of the Islamist militant network."Ships fired several missiles towards the al-Maraqisha mountains, where al Qaida elements are based. The ships are widely believed to be Americans," said one official, who asked not to be identified because of the sensitivity of the matter."We have received no information on the outcome of the shelling."The United States regularly uses drones to hunt suspected al Qaida militants in Yemen's barren hinterlands, but the involvement of naval ships is less common.