ISIS claimed responsibility for a terrorist attack that killed two people in the center of Jakarta on Thursday. If the extremist group was behind the attack, it would be the first time it has struck Indonesia.

But the Indonesian archipelago, home to the world’s largest population of Muslims, is no stranger to Islamist extremism. The al-Qaeda-linked Jemaah Islamiyah (JI) staged brutal large-scale attacks, such as the Christmas Eve bombings in 2000, where 11 churches were attacked across the country, and the 2002 Bali bombings, which killed 202 people.

Now, Indonesia finds itself facing a new threat. There are 22 local groups who have pledged allegiance to ISIS’s leader, Abu Bakr al-Baghdadi. Even though the state officially banned ISIS in 2014, the groups have yet to face any legal challenge to their dissemination of propaganda, gathering of funds or recruitment of Indonesians to fight for their hard-line vision of a “caliphate.”

… “Detachment 88 hunted terrorists, then killed or rehabilitated them,” says Rohan Gunaratna, head of the International Centre for Political Violence and Terrorism Research at Nanyang Technological University in Singapore. “Terrorists had religious counseling, were reintegrated into society and eventually became informers for the police.” Arrest of its key leaders like Bashir and the loss of support from local communities have made JI weak.