Acting Premier James Merlino condemned the actions and said Victorians needed to remain vigilant about terrorism. "We cannot ever relax ... this is something that we need to keep on top of." Professor of Global Islamic Politics at Deakin University Greg Barton said ISIS was still a global threat. "This group Islamic State is still very active. "There's no more caliphate but they haven't gone away. We'd like to think they have but this is a reminder this threat is a persistent and a resilient one," Mr Barton said. READ MORE: Police said the arrests were linked to a fire and an assault.(Nine)