ADEN - Warships shelled suspected al Qaeda strongholds in a mountainous region of southern Yemen on Thursday, government officials said.The officials, wh asked not to be named, said they believed US forces carried out the operation, though Pentagon spokesman Captain Jeff Davis quickly denied any US involvement.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 Qaeda 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 Qaeda militants in Yemen's barren hinterlands.