Minutes before 10 a.m. on Monday morning, a sudden commotion seized a Sydney chocolate shop just off Elizabeth Street. Onlookers across the street took notice. Looking from a nearby television studio, producers originally thought it was an armed robbery. But then, minutes later, they saw it: the flag. Two captive women pushed a black flag, emblazoned with Arabic in a white font, against the window. This wasn’t just a robbery, journalist Glenn Connley said.

Few details are definite. There has been no official confirmation from officials that the Sydney siege is an act of Islamic extremism. “We don’t yet know the motivation of the perpetrator — although obviously there are some indications that it could be politically motivated,” Prime Minister Tony Abbott said in statement. “There are people, even in a society such as ours, who would wish to do us harm.”

The apparent surprise in Abbot’s remarks — “even in a society such as ours” — would normally be warranted. Australia has little experience with terrorism compared with some Western Countries. It never faced anything like the Provisional Irish Republican Army or the Red Brigades. It never had to mourn mass attacks like those of Sept. 11. But now, following several Islamic State threats and radicalized residents absconding for the battlefields of Syria, Abbot perhaps has less cause for surprise than before.

Whatever the motive in Syndey’s hostage crisis, the rise of the Islamic State has rattled Australia, reflected in part by a flurry of recent legislation that significantly strengthens the nation’s security apparatus. Australia is traditionally a strong military ally of the United States, and Abbott has also pledged to fight the Islamic State, sending fighter jets and military personnel.

But its fight against radical Islam has taken place as much at home as it has been abroad. While the Soufan Group estimates hundreds of Australians fight for the Islamic State in Syria, local authorities suspect 100 more operate in Australia. Terror scares have roiled Australia for months.

In August of this year, gruesome images of a young son of an Australian militant fighting for the Islamic State circulated through the international news media. The boy, beside his father cheering him on, hoisted a severed head. Then weeks later, a man believed to be Australia’s most senior Islamic State official called for the public beheadings of random Australians, prompting the biggest counterterrorism raid in the nation’s history. As security officials dispatched increasingly ominous warnings over the threat, the Islamic State named Australia one of its five main targets for terrorist attacks. One fighter in September encouraged lone-wolf attacks.

“It is very important that attacks take place in every country that has entered into the alliance against the Islamic State, especially the US, UK, France, Australia and Germany,” the Australian reported an Islamic State magazine saying. “Every Muslim should get out of his house, find a crusader, and kill him. It is important that the killing becomes attributed to patrons of the Islamic State who have obeyed its leadership. … ‘Rely upon Allah and stab the crusader’ should be the battle cry.'”

Australia’s jihadist movement once had very different objectives. During the 1980s and the 1990s, Australia’s jihadist network focused outward, according to a 2011 paper in Terrorism and Political Violence. “For the most part these individuals engaged in paramilitary and sometimes combat overseas, but showed little motivation to attack their own country,” wrote scholar Sam Mullins.

But in the next few years, as the full impact of the Sept. 11 attacks was realized and the United States sank into the Iraq War, the conventions under which Australia’s jihadists operated started to change. Militants, even lifelong residents, looked closer to home when planning violence.

According to prominent Australian terrorism researcher Andrew Zammitt, the shift started in 2003. That year, 13 Melbourne men and nine Sydney men were arrested and charged with forming two different cells to prepare attacks. Eighteen were convicted. The arrests suggested how some Australians became “newly radicalized in the post 9/11, particularly post-Iraq War environment,” Zammitt said.

From then on, the most significant jihadist threat Australia faced was internal. “There is a persistent ‘home-grown’ jihadi element within Australia,” Mullins wrote. But in recent months, that element has suddenly changed once more — and gotten substantially more serious. The rise of the Islamic State, which attracted thousands of recruits from abroad and actively advocated terror at home, changed Australia’s jihadist movement in three ways, reported West Point’s Combating Terrorism Center.

For one, locally run recruiting services now operate in cities from Sydney to Brisbane, the article reported, funneling dozens of prospective militants to Syria. Then there’s the fact many new recruits have “close connections to past extremist violence in Australia,” suggesting familial ties among many new militants. And finally, there’s an increase in the organizational capacity of many of those cells. On Sept. 23, police arrested 18-year-old Abdul Numan Haider, who had allegedly planned to kidnap and kill a random non-Muslim, film the execution and post it to social media.

As of Monday, it was unclear what group was behind Sydney’s hostage crisis. At first, it wasn’t clear whether the plot was related to the Islamic State. Many suspected it was. But the original flag the hostages pushed against the window wasn’t an Islamic State flag.

But then the assailant offered to release some hostages. But only, he said, after he or she was given a flag of the Islamic State.