Ben Ferencz, at 97, is the last surviving prosecutor at the Nazi Nuremberg trials. He also helped liberate the death camps of Europe when he was serving in the US military.

He tells Hardtalk's Zeinab Badawi that more than 70 years after the end of World War Two, many lessons have still not been learned.

He said wars made murderers out of decent people who were trying to protect their religion, nationality or economic security.

"We have not learned that you cannot kill an ideology with a gun," he said.

Watch more clips at HARDtalk's website

You can see the interview in full on BBC iPlayer (UK only).