Jemaah Islamiah’s stated aim is to build an Islamic caliphate in Southeast Asia.
Zulkarnaen, one of the commanders of the Bali attack, was arrested on Thursday by anti-terrorism police, spokesman Ahmad Ramadhan said in a statement on Saturday.
He said the officers met no resistance.
Reuters was unable to reach Zulkarnaen or find out whether he had any legal representation. According to a UN Security Council report, he also goes by the name Aris Sumarsono.
Jemaah Islamiah’s former leader Para Wijayanto was arrested in 2019.
Stanislaus Riyanta, a security analyst, said that Zulkarnaen’s arrest could either weaken Jemaah Islamiah’s operations or “spur them into action to prove their existence or seek revenge.”