Attorney-General George Brandis and Prime Minister Tony Abbott. via

During the last week of September, some 800 Australian Federal Police officers raided houses across the western suburbs of Sydney and arrested more than a dozen men on terrorism and related charges. The most dramatic case was against a man who had been communicating with a former Sydney Muslim street preacher who had joined the Islamic State in Iraq and Syria. The preacher instructed the Sydney man to go to the city’s central business district, seize a random member of the public, behead him or her with a knife, and then drape the body in the black Islamic State flag. The killer should take an accomplice to video the whole incident and then post it onto an international jihadi website. The would-be killer, however, had been under surveillance by Australian intelligence forces for several months and, before he could act on his instructions, the police swooped.

At the same time, as Prime Minister Tony Abbott announced that Australian warplanes and special forces would join American-led operations against the Islamic State, a spokesman for that organization, Abu Muhammad al-Adnani, used the internet to urge Muslims to kill “in any manner or way” disbelieving Americans, Europeans, Australians, and Canadians. Within hours, an eighteen-year-old Islamic State supporter in Melbourne—an Australian-born youth of Afghan descent, whom undercover police had been trying to convert into an informer—arranged an apparently amicable meeting with his two police contacts. He then produced a