The common traveler's backpack carrying small bombs may now be among the leading threats to world security, experts underlined, drawing a link between this weekend's bombings in Bali to those in London in July.
Militants from the United States to Europe and Southeast Asia have used car and truck bombs and even planes to make dramatic statements. But now small, easily made bombs like those used in London appear to be the new trend.
The al Qaeda-linked group at the heart of an Indonesian probe into the three bombs that tore through restaurants packed with Saturday evening diners and killed 22 people likely drew inspiration from the London attack in July, the experts said.
"It shows a shift to small, London-style suicide bombers (like those) in Indonesia from large truck bombs," said Zachary Abuza, an expert on Islamic militancy in Southeast Asia at Boston's Simmons College.
U.S. authorities warned people of threats posed by small, home-made bombs after the July 7 attack in London's transit system that killed 56 people, putting New York on its highest level of alert since the September 11, 2001, attacks.
Security experts such as Arnold Howitt of Harvard's Kennedy School of Government said a Bali-style attack involving hard-to-detect bombs would be remarkably easy in the United States. Bomb-making materials are easy to find and security loopholes in restaurants and trains are plentiful.
But he said one element appears missing: suicide bombers.
Abuza said the simplicity of stuffing bombs into backpacks likely influenced the Bali bombers. Chilling video footage released in Bali late on Sunday showed a man entering a restaurant, followed almost instantly by an explosion.
The attack contrasts with a truck bomb detonated in the Indonesian capital Jakarta near Australia's embassy on September 9, 2004, killing three people, and to a suicide car bomb outside the JW Marriott Hotel in Jakarta in 2003 that killed 12, Reuters reports.