Questions remain about the significance of the Bondi's terrorists' recent trip to the Philippines. 

Sunday's terror attack at a Jewish celebration claimed 15 lives - and 20 people are still in hospital. 

The father and son gunmen spent much of November in a Philippines region known as a 'hotbed of Islamic extremism'.

But Australian National University criminologist Dr Clarke Jones says it's an interesting link. 

"When there was a connection to the recent terrorist attack in Bondi, I was, well, surprised there was some sort of link to the Philippines - but not surprised that terrorism is probably still active." 

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