Zakir Hussain – Jemaah Islamiyah was set up in 1993 with the aim of establishing a region-wide Islamic state. It traces its lineage to the Darul Islam group formed in West Java in the late 1940s to carry out an armed struggle for an Islamic state in Indonesia. Suppressed but never snuffed out, some of its members fled to Malaysia in the 1980s to avoid arrest and regroup.

Beginnings

The JI's first leader, Abdullah Sungkar, had fought against the Soviets in Afghanistan and sent groups of JI members to train with the Al Qaeda there. When Sungkar died in 1999, Abu Bakar Bashir took over. By then, the JI had forged links with other militant groups such as the Moro Islamic Liberation Front.

Bombings

In 2001, Singapore's Internal Security Department uncovered the JI's existence, but some in the region were sceptical that it existed.

The JI's hand in the bombing of Bali nightclubs on Oct. 12, 2002, changed things. A crackdown by the Indonesian and other regional authorities since has seen many of its leaders nabbed or dead.

The JI's ideology, however, persists. Security agencies warn that its members continue to seek to regroup, and many see the aboveground Jemaah Ansharut Tauhid (JAT) – led by Bashir – as its new front.

Its regularly updated Web site, they note, openly recruits followers to take up arms in conflict zones, and inspires others to attack easy targets.

Key terror strikes

A series of bombings struck 11 churches across Indonesia on Christmas Eve in 2000, killing 19 people and injuring over 100. Umar Patek has confessed to being the mastermind.

On Oct. 12, 2002, simultaneous bombs went off at a Bali nightspot, killing 202, many of them foreign tourists. Three plotters were involved: Imam Samudra, Mukhlas and Amrozi, who were executed by firing squad in 2008.

In August 2003, a car bomb went off at the J.W. Marriott hotel in Jakarta, killing 12 people and wounding over 150.

In September 2004, a suicide car bomber struck outside the Australian Embassy in Jakarta, killing 11 people and wounding over 100.

In October 2005, another suicide bombing at three crowded restaurants in Bali killed 22 people and hurt over 100.

In July 2009, twin suicide bombs went off at the J.West Marriott and Ritz-Carlton hotels in Jakarta, killing seven and injuring over 50.

Key JI leaders include:

Abu Bakar Bashir, spiritual leader: Currently in jail for setting up a terrorist training camp in Aceh, he had his term slashed from 15 to nine years late last year.

He was also convicted after the 2002 Bali bombings, but his four-year sentence was reduced to 18 months. In a subsequent trial, terrorism charges were thrown out and he was convicted on criminal charges leading to a 21/2-year term.

Noordin Top, chief strategist: He was shot dead in a nine-hour siege on a house in Solo, Central Java, in September 2009. He had led a hardline group that split from the JI.

Hambali, operations chief: Currently in detention in Guantanamo Bay, he was captured in Thailand in a 2003 operation and was said to be the main link between the JI and the Al-Qaeda.

Mas Selamat Kastari, Singapore JI chief: Currently in detention, he was behind a foiled plot to hijack a plane and crash it into Changi Airport. He escaped from Whitley Road Detention Centre in February 2008 and was recaptured in Malaysia a year later, before being transferred back to Singapore in September 2010.

Umar Patek, Bali blast mastermind: Currently detained and awaiting trial in Indonesia, he has confessed to carrying out the 2000 church bombings and assembling the Bali bombs in 2002. He fled to the Philippines after the Bali attacks, but was captured in Pakistan last January and sent back to Indonesia in August last year.