Twin hotel bombings that killed eight people in the Indonesian capital of Jakarta Friday are evidence that the country's main terrorist group, Jemaah Islamiyah, is viable and still may be benefiting from support from al Qaeda, a U.S. counterterrorism official said.
The suicide bombers who attacked the JW Marriott and the Ritz-Carlton hotels also injured more than 50 people, according to Indonesian law enforcement. At the Marriott, investigators found evidence that the bombs were assembled by terrorists posing as guests who checked in earlier and put together the devices in their rooms.
The attacks were the first of their kind since September 2004, when Jemaah Islamiyah (JI) targeted the Australian Embassy in Jakarta, killing 10 and wounding hundreds.
While U.S. officials could not say for sure that JI was responsible, "in that part of the world they rise to the top of the list of suspects," said a U.S. counterterrorism official. "They have a long history of attacking people in the region. The hotels are symbolic, and the attacks reflect their long-held hostility toward the Indonesian government, the U.S. government and its allies."
The official, who spoke on the condition of anonymity due to the nature of his work, said the hotels were obvious targets because they are owned by Western chains and frequented by foreigners. The Marriott was bombed by JI in 2003.
Scott Atran, an expert on Islamic terrorism who teaches at the University of Michigan, said Friday's attacks bore the hallmarks of a JI splinter group led by Malaysian-born Noordin Mohammad Top.
A former accountant, Noordin was implicated by Australian forensic experts in both the 2003 Marriott and the 2004 Australian Embassy attacks.
"The bombings today in Jakarta smell to me like Noordin Top's network," Mr. Atran said, citing the choice of the Marriott for the second time and the use of suicide bombers.
Noordin built the JI splinter group around his personal relationships.
Mr. Atran doubted there was any "formal JI involvement" by Abu Bakr Ba'asyir, JI's purported spiritual leader, and others of the old JI command.
Ba'asyir was imprisoned on charges stemming from the Bali attacks in 2002 but later was acquitted.
The counterterrorism official, meanwhile, said that authorities were "looking into" the possibility that al Qaeda helped plan the latest bombings.
No Americans were killed in Friday's incidents although several were reported to have suffered minor injuries.
President Obama and Secretary of State Hillary Rodham Clinton expressed serious concerns.
"Indonesia has been steadfast in combating violent extremism and has successfully curbed terrorist activity within its borders," Mr. Obama said. "However, these attacks make it clear that extremists remain committed to murdering innocent men, women and children of any faith in all countries.
"The American people stand by the Indonesian people in this difficult time, and the U.S. government stands ready to help the Indonesian government respond to and recover from these outrageous attacks as a friend and partner," Mr. Obama added.
U.S. and Indonesian authorities have put enormous pressure on JI in recent years, resulting in a decrease in attacks, but reports that JI has been dismantled were "a false assumption," the U.S. counterterrorism official said.
"Bottom line is: JI remains a threat, and we're chasing down every possible lead," the official added.
In October 2002, the group was responsible for a triple bombing in Bali that killed more than 200 people at nightclubs.
In Friday's attacks, the terrorists evaded metal detectors and vehicle inspection checkpoints in place since previous bombings.
The Associated Press reported that hotel X-ray machines, set up to detect bombs, did not reveal dangerous material hidden in the luggage of the bombers, who apparently brought in the various components of the bombs at different times.
JI used to have several hundred members across Malaysia, Indonesia, the Philippines, Thailand and Australia. The group, allied with al Qaeda, received military training and sought to build an Islamic state.
During the 1980s, 60 Indonesian and Malaysian members of the group reportedly traveled to Afghanistan to aid anti-Soviet Mujahadeen fighters. Some attended al Qaeda training camps and developed close ties with the organization.