(SOUND BITE) (English) U.S. ATTORNEY GENERAL WILLIAM BARR, SAYING: "This was an act of terrorism." U.S. Attorney General William Barr said on Monday that the fatal shooting of three Americans at a naval base in Pensacola, Florida last month was "an act of terrorism," and that the Saudi Air Force officer who shot them appeared to have acted alone. (SOUND BITE) (English) U.S. ATTORNEY GENERAL WILLIAM BARR, SAYING: "The evidence shows that the shooter was motivated by jihadist ideology... He also posted other anti-American, anti-Israeli and jihadi messages on social media, including two hours before his attack." Saudi Air Force trainee Mohammed Alshamrani was shot dead by a deputy sheriff, ending the attack on December 6th. And while Barr said the investigation found no evidence of assistance or advanced knowledge of the attack by any other Saudi trainees, it did find that 21 cadets from the kingdom of Saudi Arabia possessed what Barr called "derogatory material" and announced they'd be leaving the United States. (SOUND BITE) (English) U.S. ATTORNEY GENERAL WILLIAM BARR, SAYING: "Seventeen had social media containing jihadi or anti-American content. However, there was no evidence of any affiliation or involvement with any terrorist activity or group. Fifteen individuals, including some of the 17 I just mentioned - so there is overlap - had some kind of contact with child pornography... the kingdom of Saudi Arabia determined that this material demonstrated conduct unbecoming an officer in the Royal Saudi Air Force and in the Royal Navy. And the 21 cadets have been disenrolled from their training curriculum in the U.S. military and will be returning to Saudi Arabia later today." The shooting, which killed three American sailors and wounded eight other people, has further complicated U.S.-Saudi relations. It's also widened a rift between the Department of Justice and Apple, which Barr said has not been helpful to the FBI's investigation. (SOUND BITE) (English) U.S. ATTORNEY GENERAL WILLIAM BARR, SAYING: "The shooter possessed two Apple iPhones, seen here on the posters. Within one day of the shooting, the FBI sought and received court authorization based on probable cause to search both phones in an effort to run down all leads and figure out with whom the shooter had been communicating. We have asked Apple for their help in unlocking the shooter's phones. So far, Apple has not given any substantive assistance." The top U.S. law enforcement official said Apple's encryption for iPhones has made it increasingly difficult to search the devices... (SOUND BITE) (English) U.S. ATTORNEY GENERAL WILLIAM BARR, SAYING: "It's becoming a grave problem." ...and asked the company to help authorities find a solution. (SOUND BITE) (English) U.S. ATTORNEY GENERAL WILLIAM BARR, SAYING: "We call on Apple and other technology companies to help us find a solution, so that we can better protect the lives of American people and prevent future attacks."