PENSACOLA, Fla. (Reuters) - The Saudi airman accused of killing three people at a U.S. Navy base in Florida appeared to have posted criticism of U.S. wars and quoted slain al Qaeda leader Osama bin Laden on social media hours before the shooting spree, according to a group that tracks online extremism.

Federal investigators have not disclosed any motive behind the attack, which unfolded at dawn on Friday when the Saudi national is said to have begun firing a handgun inside a classroom at the Naval Air Station Pensacola. U.S. Defence Secretary Mark Esper said during a public appearance on Saturday he was not ready to label it an act of terrorism.