During the interview, he told Customs officials he was addicted to the images.
Offenders often tried to deny or minimise their behaviour, blaming addiction, but they were still viewing images of a horrendous crime where innocent children were exploited and victimised, he said.
"Children often don't even understand they are victims until later. This should never be described as pornography ? these are images of crimes committed against children who are too young to understand.
"In this case, Stratton was viewing horrific abuse images and keeping them to exchange with others," Mr O'Brien said.
"Our ultimate aim is to save and protect victims, and it is unacceptable their images are used as a trading commodity."
Offenders should seek help, he said.
"It is never okay - you are causing serious harm to innocent victims and yourselves.
"Don't do it, you will be caught - [instead] seek help from professional agencies like the SAFE network or Well Stop network."