When the press says many are from South Asia, where is that? On my Atlas that means Indonesia, Singapore, Philippines, at a pinch, Sri Lanka, really?
Indonesia for one. They have healthy extreme Muslim groups, although the Indonesians have been giving them a good whack over the last 5 years.
They don't suffer from the west's inhibitions about opening fire so to speak
Edit
Jemaah Islamiah - Southeast Asian militant Islamist terrorist organization dedicated to the establishment of a Daulah Islamiyah (regional Islamic caliphate) in Southeast Asia.