But just as Al Qaeda lost strength elsewhere in the world, Jemaah Islamiyah was supplanted in Indonesia by other militant groups that pledged allegiance to the Islamic State. In one of the most shocking episodes, an entire family — mother, father, two teenage sons and two younger daughters — blew themselves up in back-to-back attacks on three churches in Surabaya, the second largest city in Indonesia, in May last year.
The Islamic State claimed responsibility for those assaults, which killed 12 people, describing them as a “martyrdom operation.”
Within another day, two other families in Surabaya fatally set off their own bombs, one at a police station and another in a premature misfire in their own apartment.
All three families appeared to be linked to Jamaah Ansharut Daulah, an Indonesian militant organization that has pledged allegiance to the Islamic State. Since then, about 300 people believed to be connected to Jamaah Ansharut Daulah have been rounded up by Indonesian counterterrorism forces.
Surabaya is a multiethnic, multifaith city, in a country run by a secular government. The southern tip of the Philippines, while majority Muslim, has a significant Catholic minority. And Malaysia, from where at least 130 people, according to Malaysian counterterrorism experts, have traveled to Iraq and Syria to join the Islamic State, balances a Malay Muslim majority with large ethnic Chinese and Indian populations.
Yet militants in all three countries have over the decades called for those sharing an ethnic Malay heritage to create a crescent-moon-shape caliphate across the region. Other extremists have expressed more isolated concerns for local autonomy.
Southeast Asian militants gained battlefield experience in Afghanistan and ideological guidance in Pakistan, Saudi Arabia and Yemen. More recently, hundreds of Filipinos, Indonesians and Malaysians traveled to Iraq and Syria to act as foreign fighters for the Islamic State, forming their own corps with its own recruitment tools online.