'Smart' bomb may hold key to success

A new type of "smart" missile capable of finding hidden caves from a distance of 1,000 miles and detonating inside may offer the West the crucial tool it needs in its war against Osama bin Laden.

The US Defence Department's ''bunker-buster" is not a new idea. It is the latest version of a bomb that was hastily developed at the start of the Gulf War with the aim of penetrating the thick concrete bunkers used by the Iraqi leader, Saddam Hussein.

The GBU-28 – GBU stands for guided bomb unit – was rushed into service 10 years ago after being designed and produced in no more than a month.

Guided by lasers and with a pay-load of 630lbs (285kg) of high explosive, it was one of the few pieces of allied ordnance – short of a nuclear warhead – able to penetrate heavily armoured subterranean hideouts. A new satellite guided version – the GBU-32 – was produced for Nato's 1999 air war against the Serbs.

But Bob Sherman, of the Federation of American Scientists, a think-tank that monitors weapons development, warned that no amount of satellite-guided accuracy would necessarily deliver the kind of knockout blow the West craves.

"It depends how deep in the caves these people are," he said. "If they are at the end of a long system, these bombs may be less effective. But if you can get a bomb into the entrance of a cave, the walls will contain the explosion and the lethal effect will carry deeply."

Several companies, including BAE Systems, are trying to develop two-stage weapons to destroy inaccessible targets.