US Secretary of Defence Jim Mattis, the former general who has spoken at the head of Marine formations ready for battle, has found a new audience for his blunt wisdom: budding high school journalists.

Teddy Fischer, a student at Mercer Island High School in Washington state, landed a rare exclusive with Mattis, who has granted few interviews after he was tapped to lead the Pentagon. Mattis dissected topics from over-politicisation of US discourse to navigating combat operations in Syria with Russia and Iran. "History will show you not all the answers, but it'll tell you a lot of the questions to ask and furthermore, it will show you how other people have dealt successfully or unsuccessfully with similar type issues," Mattis told the school paper the Islander.

Fischer tracked down Mattis after the Washington Post inadvertently published a photo with his private phone number, and to Fischer's surprise, he returned the call.

Fischer asked why he decided to do an interview. Mattis said he also grew up in Washington state. "I've always tried to help students because I think we owe it to you young folks to pass on what we learned ... so that you can make your own mistakes, not the same ones we made."