Australia's intelligence chief says it's "almost guaranteed" that the nation's domestic terrorism threat level will be raised in the future.
Late last year, ASIO boss Mike Burgess lowered the terrorism threat level from probable to possible - a decision that wasn't taken lightly.
While Australia remained a potential terrorist target, he said, there were fewer extremists with the intention to conduct an attack onshore than there were when the threat level was raised in 2014.
At the time of making the threat change, Mr Burgess said it remained "entirely plausible" there would be a terrorist attack in Australia within 12 months and that ASIO's biggest concern was individuals and small groups who could move to violence without warning.
"Tragically, all that came true just a few weeks later."
The Wieambilla tragedy - resulting in the murders of two Queensland police officers and a member of the public - in December showed how even with a lower threat level tackling terrorism remained challenging.
Mr Burgess described the shootings, carried out by Gareth, Nathaniel and Stacey Train, as an "act of politically motivated violence, primarily motivated by a Christian violent extremist ideology".
But ASIO did not find evidence the killers embraced a "racist and nationalist ideology or were Sovereign Citizens, despite their anti-authority and conspiratorial beliefs".
More broadly, he said the reach of extremist content online meant individuals were radicalising within days or weeks.
"So the time between flash to bang is shorter than ever," Mr Burgess said in his latest annual threat assessment, delivered in Canberra on Tuesday.
"The radicalisation of minors is another concerning trend."
The ASIO boss warned terrorism developments overseas could resonate in Australia.
"In our near region, under ISIL's influence, religiously motivated violent extremists are adapting their methods, with suicide bombings becoming more common in the southern Philippines, as well as attacks by females and families in the region more broadly," Mr Burgess said,
"Despite strong counter-terrorism pressure in the Philippines and Indonesia, ISIL-aligned violent extremists will continue to plan and conduct simple, often opportunistic attacks, primarily directed against local security forces and sectarian targets over the next six months."
Terrorism hotspots in Africa, the Middle East and South Asia - where many Australians live and work - were also being watched.
