A five-minute primer on an issue making headlines
The release from jail last week of Muslim leader Abu Bakar Bashir has renewed fears about the dangers posed by the terrorist group he is accused of leading.
Was Bashir involved in creating Jemaah Islamiah?
The organisation commonly known as JI is believed to have been formed in Malaysia in the late 1980s by a group of exiled Indonesian extremists. Around two decades earlier Mr Bashir and Abdullah Sungkar resuscitated the Darul Islam sect, a radical movement whose goal was to create a single Islamic state under sharia law across Southeast Asia - from Thailand in the north to the far south-eastern tip of the Indonesian archipelago. Before fleeing to Malaysia in 1982 both men spent several years in jail as the Suharto regime cracked down on anti-government groups. They returned in 1998, when Suharto was deposed.
When did JI turn violent?
After several key members returned from Afghanistan, where they fought for the mujahedeen against Soviet occupation. There, many of the personal connections that define today's global network of Islamic terrorist groups were formed, including links between al-Qaeda and JI. Key to JI's change in strategy was mujahedeen Riduan Isamuddin - better known as Hambali - who met Mr Bashir in the early 1990s. Hambali became JI's military leader, and is said to have orchestrated the group's metamorphosis into small and autonomous terrorist cells scattered across Southeast Asia.