The Sydney-based anarchist group Black Rose Syndicat has vowed to cause ''chaos and mayhem'' at the G20 summit in Brisbane in November 2014, while the Australian cell or ''affinity group'' of the international online anarchist group Anonymous has announced it will sabotage the G20 through its ''Operation Mayhem''.
Black Rose claims it ''is an anonymous syndicat whose aim is the propagation of anarcho-syndicalist and other revolutionary propaganda'' and has no members because it is against ''all hierarchical structure''.
It uses command and communication chains that are flexible to provide greater security. More disturbingly, it is encouraging sympathisers to apply for jobs with the G20 taskforce to be on the inside ''to turn it [the G20 security operation] inside out''.
The Black Rose Syndicat announced its formation as a ''sand dune type syndicat'' in cyberspace. It is thought to be based at Sydney University although some politically-active Sydney University students say most members are not students there and are motivated mainly by the opportunity to cause violence.
Clearly, spelling and grammar are not high on their agenda. Black Rose seems to be first cab-off-the-rank of a number of web-based extremist groups that will be active in the lead-up to the G20.
In December 2013, Anonymous Australia vowed to release a list of more than 500 police and military officers it claims have infiltrated activists groups in Australia with the aim of gathering information ahead of the G20.
The security precautions taken by anarchist groups mean it is difficult for security agencies to infiltrate them and identify the organisers. This is a turnaround from the situation in the past where police and ASIO could infiltrate or cultivate informants in potentially violent groups before a major international event, as was done before the World Economic Forum in Melbourne in September 2000.
The Black Bloc, the best known international anarchist co-operative, was probably the first to use the internet and social networking to encourage ''flash violence''. Those who subscribe to their views are encouraged to dress in black, wear hoodies, sunglasses and ski masks and bring motorcycle helmets to protests.
The primary targets for anarchist attacks are symbolic ones, normally facilities connected to government (because anarchists believe in a state-free society), multinationals and banks (because they exploit the people), and police and surveillance cameras (tools of the state). No doubt some anarchists simply enjoy violence and destruction of property.
Anarchists deliberately choose international economic meetings to try to persuade the delegates that ''the people'' reject their attempts to exploit them, and to get maximum publicity from the presence of the international media.
Having major international meetings in cities such as Brisbane inevitably leads to the disruption of normal activities and potential for damage to the city, as occurred with the World Trade Organisation meeting in Seattle in November 1999. The ''Battle in Seattle'' involved at least 40,000 demonstrators and caused considerable damage to the city.
In 2010, the G20 summit was held in Toronto, Canada. The protests were mainly peaceful but some protesters used Black Bloc tactics to cause damage to at least 40 businesses at a cost of nearly $1 million.
What can be done in the lead-up to such events by the security authorities? The British police and MI5 adopted proactive tactics for the London Summer Olympics in 2012. They identified all British potential troublemakers, who were then warned-off from travelling to London or were physically prevented from doing so.
Troublemakers who lived in London were not allowed near the Olympic venues. Known activists from abroad were not allowed to enter the country.
The Queensland Police Service is responsible for providing security to G20 delegates and for all meeting and accommodation venues, motorcade routes and any other event associated with the Brisbane meeting.
It will involve a complex security operation to safeguard visitors and try to minimise disruptions to inner-city residents and businesses, but roads between the central business district and Brisbane Airport will be closed. All public transport services travelling close to event venues will be cancelled.
The Queensland government's G20 (Safety and Security) Bill 2013 contains additional police powers for the G20 period, such as the creation of restricted zones and an outer security buffer zone. Police at the G20 will have the power to search persons and vehicles and premises without warrant, including the conduct of strip searches. A prohibited-persons list will be established by the Queensland police commissioner and there will be a presumption against bail for the limited period of the meeting.
Because of the high cost of holding such events, they do not generate income; in fact quite the opposite. The likely cost of the G20 in Brisbane to Australian taxpayers will be about $450 million - against an anticipated income for Queensland of about $100 million. Australia is the current chairman of G20, which means that the G20's main value to Australia will be giving our Prime Minister a chance to strut his stuff under the international spotlight, and host, and hopefully influence, leaders from the world's most powerful economies.
About 4000 delegates are expected and about 2500 media representatives. The delegates are probably not going to see much of Brisbane because of exclusion zones and security restrictions.
Security for the event will involve more than 1500 personnel. Brisbane was selected over Sydney because the city was deemed better equipped to cater for the significant increase in plane arrivals and the Sydney Convention and Exhibition Centre will be undertaking renovations.
It would be a good idea for most Australians to stay away from Brisbane in mid-November 2014. Those who live in central Brisbane would be well advised to go somewhere else.
Clive Williams is an adjunct professor at Macquarie University's Centre for Policing, Intelligence and Counter Terrorism and a visiting professor at the ANU's Centre for Military and Security Law.