Around that time there was a "September Eleventh" subversive Group, that were considered threat to Australia and the West Australian group were looked at as possible members, even though the Group had it's origins in Spain and the expulsion of Muslims by the ruling Clergy (Catholic) of the Day. onepeterfive.com/the-top-4-reasons-september-11th-is-significant-to-islam/
Even prior to the attack on World Trade Centre in New York in 2001 the group were on a "Watch List" by Democratic Govt Agencies in UK, USA and Australia. Though-out the Nineties the date was regarded as a significant risk to potentially create damage to Public Buildings. The 1993 May explosions in WA was looked at as being a pre-cursor to a massive attack on the World by "Spooks" from all Agencies - but as in the article the outcome was attributed to meteorite strike/s.
As it turned out the Japanese group had no known links to other September Eleven Groups in Australia at that time.