A teenager allegedly fuelled by racist and nationalist views has faced court accused of planning a terrorist attack.
The 17-year-old Canberran has been behind bars since November after police allegedly found violent, extremist material during a search.
Officers later uncovered further evidence and on Tuesday the teenager appeared in ACT Children's Court charged with planning a terrorist attack and sending violent extremist material.
Young Australians' exposure to this kind of propaganda was alarming, Australian Federal Police counter-terrorism assistant commissioner Peter Crozier said.
"Violent extremist material is circulated by terrorist organisations to promote violence, hate and division within Australian society," he said.
"It is our job to defend and protect the Australian community, and we will relentlessly pursue those who seek harm to our democracy or our social cohesion."
The teenager is the first person to be charged with planning a terrorist act in the ACT.
In March, a 16-year-old from Sydney's inner west faced court after police searched a number of devices and allegedly found information relating to extremist violence.
Officers allege the boy, driven by a mixed ideology, had made plans for acts of violence.
He was charged with collecting and making documents likely to facilitate a terrorist act, and possessing violent, extremist material.
A 15 and 16-year-old from the NSW New England area were arrested in April after police seized handwritten notes and literature that allegedly contained extremist references.
The accused offenders' young ages have prompted calls for schools, parents, social services and technology companies to act and prevent youth access to extremist content.
"Recognising early signs of changes in a young person's behaviour can play a crucial role in guiding young people to safe and supportive pathways," ACT Policing Deputy Chief Richard Chin said.
"Strengthening awareness and confidence in trusted and supportive networks is a key element to preventing radicalisation and protecting young people from harmful influences."
If someone was distancing themselves from their social circles, using hateful language, developing a fixation on conspiracy theories or spending increasing amounts of time on fringe internet forums, it may be a sign they are vulnerable to radicalisation, police warned.