''Very soon after I could hear an explosion and people screaming in the street,'' he said.

It was the start of the horror of the 9/11 terrorist attacks on the United States which the world will soon pause to remember 10 years on.

John went down to the street where he heard the second plane hit the World Trade Centre but did not pause to watch the buildings crumble. He just wanted to get out of there.

''I decided to go home and shut myself in my apartment and watch it on television because I was afraid of the dust,'' he said.

''If they were well-organised enough to pull that off, an accomplishment of that scale, they were well-organised enough to have the plane loaded up with anthrax or something similar so when the buildings collapsed it would spew all over the city. So I wasn't going to be out in the streets.''

While John was just blocks from the unfolding disaster, his wife Valerie was stranded in San Francisco, unable to board her flight to New York. She was about to learn that she had a particularly poignant connection to the tragedy.

At the time she was the director for the Centre for Tax System Integrity at the Australian National University looking forward to working with a young American academic Leslie Whittington, who was about to start a sabbatical at the centre in Canberra.

Ms Whittington was bringing her husband and their young daughters, Zoe, eight, and Dana, three, to Australia. The children couldn't wait to see their first kangaroo.

''There was just great excitement at their end,'' Valerie said.

Instead, on that sunny Tuesday morning in September, the family, en route to Canberra, perished as their American Airlines flight slammed into the Pentagon.

Valerie was in a San Francisco hotel room when John called to tell her he had seen the names of the family flash on the television screen, among the horrible roll call of the presumed dead. ''It was just so very sad and heartbreaking,'' she said.

Valerie ended up dedicating a book called Taxing Democracy - which Ms Whittington would have worked on while she was in Canberra - to the young mother.

She takes some solace from the fact Ms Whittington's mother and stepfather tried to do positive work despite enduring an unthinkable loss. They used compensation from the United States government to promote Ms Whittington's favoured causes, including education and women's rights. They started a website to encourage people to plant flowers in honour of their grand-daughters.

''I actually really found the family's response inspiring,'' Valerie said. ''They were absolutely grief-stricken but they were determined to make the world a better place and that's what I think we should do, too.''

A decade later, John still has vivid images from the day and its aftermath. He remembers seeing a dog wandering the streets, looking lost, still with its leash attached. ''It's a weird thing to get upset about but you couldn't help but think what happened to its master or mistress,'' he said. He also recalls the terrible loss at his neighbourhood fire station - the one officer who had to stay back and man the station was the only one from the crew who survived September 11. John, an Australian Research Council Federation Fellow and founder of RegNet (the Regulatory Institutions Network) at the ANU, is also deeply interested in the aftermath of September 11 because his work is about peace building.

He has just spent a month in Afghanistan and is writing a paper with Afghan co-author Ali Wardak called Is Killing the Taliban a Good Idea? He thinks it's not.

''I think a ceasefire now is probably a good idea,'' he said. ''The leaders of the Taliban are safe in Pakistan. They are killing a lot of mid-level Taliban who are being replaced by younger, more ruthless men, many of whom have spent their whole lives in Pakistan and are under the control of the Pakistan intelligence so we're not achieving much.''