The Pentagon is developing a stinkbomb powerful enough to drive away hostile crowds in a move towards what will almost certainly be classified as "stench warfare".

No longer will demonstrators be able to say that they smell a rat when they spot the police or army gathering to halt their progress - they will be smelling something altogether more subtle.

The new stinkbomb will be part of the police and army's arsenal for dealing with the increasing number of violent protests against globalization that have been taking place wherever world leaders and financial institutions gather around the globe, from Seattle in 1999 to Gothenburg last month.

"It would give us an offensive capability against large and unruly groups of people, if they are unwilling to move or are openly hostile," a Pentagon spokesman told the New Scientist magazine, which this week published details of the invention. "And it would minimize the risk to our people and to the antagonists."

The researchers who have been working on the project said there was a close link between a particular kind of smell and fear, and that a particular odor can activate tissue deep within the brain.

The aim would be to use such a smell to send a panic through the ranks of demonstrators.

Pam Dalton, a cognitive psychologist at the Monell Chemical Senses Center in Philadelphia who is leading the search for a more sensitive stinkbomb, has tested smells on volunteers of different ethnic origins to try to find a formula that affects everyone.

She is reported to have found two odors that appear to transcend culture; a mixture of the two could form the basis of the new weapon.

This could also be seen as the authorities getting their own back for the use of odor warfare by protesters. A favorite ploy has been to lob lion dung taken from zoos and safari parks at police horses, who panic at the lions' scent and throw their riders.

© Guardian Newspapers Limited 2001

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