Lovitt Technologies, a defence manufacturer based in Greensborough, northeast of Melbourne, was targeted shortly before 4am on July 5, 2025.
An unnamed extremist group has claimed responsibility for the attack, which saw multiple vehicles set alight and the business vandalised, in an online video, the Victorian Joint Counter Terrorism Team alleges.
The unit, which includes Victoria Police, Australian Federal Police and ASIO, is investigating whether the group were "far-left extremists" motivated by anarchist and revolutionary ideologies.
Investigators have not released the video, but images appear to depict a masked individual setting something alight while standing at a podium.
The offenders appear to be standing before a Palestinian flag and are alleged to have outlined a number of grievances in support of the Middle Eastern country.
Police said they may have been motivated by the belief the business was part of the Australian Defence Force's supply chain.
They allegedly gave advice on how to create incendiary devices similar to one suspected of creating the fire that damaged vehicles at the manufacturing business.
Following the incident, police said the offenders left by a back fence and travelled on e-bikes southwest along Plenty River.
If caught and convicted, they could face life in prison for federal criminal offences related to the commissioning and preparation of a terrorist act.
Victoria Police Detective Acting Superintendent Anthony Wheatfill said the alleged attack could have had devastating consequences.
"That anyone would use such violent and dangerous methods to express a political or social viewpoint is unacceptable," he said.
"Fire is dangerous and unpredictable and criminal offending of this nature - which has the potential to significantly impact our community and lead to deaths or serious injury - will not be tolerated."
Any members of the public with knowledge of the offenders or the attack or those in the area at the time have been urged to contact police.
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