A swift CT police response:
Greece's counter-terrorism squad on Tuesday announced that its investigations have led to the discovery of a criminal organisation allegedly linked to the extreme right that may be involved in explosions, raids and arsonist attacks. It announced that coordinated operations were launched on Tuesday morning in Attica and other areas of Greece.

According to the police, quoted by the Ana-Mpa agency, six persons were detained and will later be placed under arrest as suspected members of the organisation, as well as for their suspected participation in a series of attacks involving explosions, firebombs and raids on locations frequented by migrants and members of anti-establishment groups.
Link:http://www.ansamed.info/ansamed/en/n...2e70f81e4.html

If law enforcement is the route taken, the test will be if they are charged with offences and later convicted.