Two males picked up in counter-terrorism raids in Sydney had travelled or tried to travel to Syria, police say.
They are a man, 24, and a boy, 17, and both have been charged with foreign incursion offences.
The man is linked to al-Nusra, an affiliate of al-Qaeda, while the teen tried to join Isis (Islamic State).
"They will face the full force of the law," Australian Federal Police Assistant Commissioner Neil Gaughan said.
According to media reports the man who has previously fought in Syria was arrested in Birrong after his car was intercepted by police.