A deadly bunker-busting bomb built on a principle roundly denounced by human rights groups in the past was used by US forces for the first time in Afghanistan, a military official acknowledged.
The thermobaric bomb BLU-118S was among the more than 80 pieces of ordnance dropped on Saturday by US warplanes south of the Afghan city of Gardez where intelligence had discovered a concentration of Taliban and al-Qaeda fighters.
"We used one thermobaric bomb in that operation," Navy Lieutenant Commander Matthew Klee, a spokesman for the Central Command, told AFP. "It was the first time we used it."
The bomb, which belongs to the category of so-called fuel-air munitions, is capable of penetrating deep underground to reach hidden command bunkers or caves and explode upon hitting its target, according to experts and defense officials.
Its explosive charge is designed in a way that allows the attacker to practically pulverize all occupants of the underground structure.
"It works as a combination of a shock wave and a fuel explosion," Klee explained. "The first explosion spreads flammable aerosols through the underground complex. Then, the second ignites the fuel."
According to independent experts, the bomb, once detonated, produces rapidly expanding shock waves flattening anything near the epicenter of the aerosol fuel cloud, and capable of causing extensive damage far beyond the immediate strike area.
In addition, shock waves produced by the BLU-118S are capable of navigating underground labyrinths and literally leaving no stone unturned, according to Klee.
"When the shock wave from a normal bomb hits a wall it stops," said the spokesman. "With BLU-118, the shock wave goes around the corner."
The Russian army reportedly used a version of a fuel-air bomb in the breakaway North Caucasus republic of Chechnya in late 1999, against mountain hideouts of local separatist rebels, according to Human Rights Watch, an international monitoring organization.
In a letter sent in February 2000 to Vladimir Putin, then Russia's acting president, the group warned that fuel-air explosives, which are compared by some experts to low-yield nuclear bombs, could cause massive loss of life especially in or near populated areas.
"Their use against populated areas would violate international norms on indiscriminate attacks," said Joost Hiltermann, Human Rights Watch's top weapons expert.
Klee said the US military was aware of Moscow's use in Chechnya of a bomb built on a similar concept but assured that the US BLU-118S "falls under the guidelines of the Geneva Conventions."
The spokesman declined to disclose why the Pentagon had chosen to use such a powerful munition against a cave complex near Gardez, saying only that "a pocket of Taliban and al-Qaeda resistance" had been discovered in the area.
Asked if Osama bin Laden, the suspected mastermind of the September 11 attacks, could be hiding in the area, Klee said, "We are not going to speculate. We don't know where he is."
According to a statement released by the Central Command, fighting continued south of Gardez into early Sunday.
"Firefights have been intense at times in heavy combat actions," the statement said. "The exact size of the enemy forces occupying a series of cave complexes is not known."
One US soldier and three Afghan troops have been killed so far in the operation, and an unspecified number of US and Afghan forces have been injured, according to the command.
Copyright 2002 AFP