Jemaah Islamiyah (JI) is an Indonesia-based clandestine terrorist network formed in the early 1990s to establish an Islamic state encompassing southern Thailand, Malaysia, Singapore, Indonesia, Brunei, and the southern Philippines. Its operatives, who trained in camps in Afghanistan and the southern Philippines, began conducting attacks in 1999. The network’s existence was discovered in late 2001 after Singaporean authorities disrupted a cell that was planning to attack targets associated with the US Navy. JI is responsible for a series of lethal bombings targeting Western interests in Indonesia and the Philippines from 2000-2005, including attacks in 2002 against two nightclubs in Bali that killed 202 people; the 2003 car bombing of the JW Marriott hotel in Jakarta that killed 12; the 2004 truck bombing of the Australian Embassy that killed 11; and the 2005 suicide bombing of three establishments in Bali that killed 22. A JI splinter group led by Noordin Mat Top in July 2009 conducted suicide bombings at two hotels in Jakarta.
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Southeast Asian governments since 2002 have arrested more than 300 suspected terrorists, significantly degrading JI’s network. Thai authorities detained the network’s operations chief in 2003. Indonesian police killed JI’s most experienced bombmaker in 2005 and arrested its two senior leaders in mid-2007. Malaysian authorities arrested two senior JI operatives in Kuala Lumpur in early 2008 and in April 2009 recaptured fugitive Singapore JI leader Mas Selamat Kasteri, who escaped from his Singaporean prison cell in early 2008. Indonesian police in September 2009 killed Noordin Mat Top.
Since 2009, JI has been overshadowed by the activities of its splinter groups and other Indonesia-based terrorists, some of whom are experienced operatives previously affiliated with JI; others are convicted terrorists who completed prison sentences and have since resumed their activities. Indonesian terrorist Umar Patek—arrested by Pakistani authorities in Abbotabad in January 2011 and repatriated seven months later—was convicted in June 2012 for his role in the 2002 Bali bombings and sentenced to 20 years in prison. In November 2012, Philippine security forces killed senior Indonesian JI leader Sanusi.
INFORMATION UPDATED SEPTEMBER, 2013.