The arrested leader of terror group Jemaah Ansharut Tauhid (JAT) travelled to Syria last year for training and took an oath of allegiance to the Islamic State in Iraq and Syria (ISIS), according to the head of Indonesia's national counter-terrorism agency BNPT.
Afif Abdul Majid, 59, whom police arrested over the weekend, had travelled through Malaysia and Turkey to the Syrian border with a group from HASI, seen as the humanitarian wing of the Jemaah Islamiah (JI).
On his return, he began organising activities to rally support for ISIS and recruit new members to fight there, BNPT chief Ansyaad Mbai told The Straits Times.
Afif, who had sanctions imposed on him by the United States Treasury last year, is the most prominent radical to be arrested in recent days in an ongoing crackdown on pro-ISIS networks in Indonesia that has won considerable support from mainstream Muslim groups.
Police say Afif was involved in financing terrorist training in Aceh in 2010.
Just last month, he led several hundred supporters of hardline groups at a mosque in Solo to pledge allegiance to ISIS leader Abu Bakr al-Baghdadi.
Analysts say ISIS supporters do not have the capability to mount a major attack at the moment, but the fear is they may gain wider support.
The Soufan Group, a security consultancy, said in a report that from 50 to perhaps as many as 200 Indonesians, together with at least 30 Malaysians, have already travelled to Syria to fight alongside ISIS and other rebel groups, frequently under the guise of humanitarian organisations.
"Just as the JI sent Indonesians, Malaysians and Singaporeans to Afghanistan for military training in the 1980s, and they returned home to carry out attacks, these South-east Asian countries now fear that militants may similarly return from Syria and Iraq, with terrorist training, to mount new campaigns," it added.
A handful of these militants have reportedly died in the fighting. Indonesia's Quran Tempo newspaper reported this week that they included former terror convict Abdul Rauf, who recruited several plotters of the 2002 Bali bombings that killed 202.
Mr Ansyaad said a key reason why support for ISIS has been rising rapidly is that the existing infrastructure - older terrorist groups that seek to establish a caliphate and impose their version of Islamic law in Indonesia - remains resilient.
"In a way, this is a continuation of the JI. Their goals are the same," he said. "So are their targets: Crusaders, Jews, and America, as well as Muslim governments that don't follow syariah."
"They just wear a new jacket," he added.
Mr Ansyaad noted that 18 terror inmates in maximum-security Nusakambangan prison have taken an oath of loyalty to ISIS. Photos of inmates doing so with ISIS flags before JAT emir Abu Bakar Bashir created a stir and led the authorities to impose stricter limits on them, including on visitors.
But Bashir's son Abdul Rohim and recently removed JAT leader Mochammad Achwan have left the group and formed a new outfit, claiming disdain for ISIS' massacre of fellow Muslims in the Middle East.
Terrorism analyst Muh Taufiqurrohman told The Straits Times that while Afif's arrest will weaken or slow down ISIS recruitment in Java, it would be better if other recruiters were also arrested soon to deter would-be militants.
"The crackdown is also good in dividing radical groups such as JAT, weakening its capacity to operate. However, it also pushes ISIS supporters to go underground," he said.
"In addition, the split of JAT and its affiliated groups pushes their members who join ISIS to be more radical and likely to carry out attacks in the future."
This article was first published on August 14, 2014.
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