US military malodorant missiles kick up a stink

IMAGINE being hit by a smell worse than anything you've ever encountered. It combines the reek of sewage with pungent rotting meat. It is nauseating, and so intense that you rush for the door. That is what it would be like to experience a malodorant - a non-lethal weapon being developed by the US to drive targets out into the open.

The use of chemical agents in war is banned under the international Chemical Weapons Convention (CWC). Even compounds often used by police, such as tear gas, are prohibited in war.

But the US Department of Defense (DoD) thinks it has found a loophole that will allow superpowered stink bombs to be added to the US military arsenal.

According to Kelly Hughes, spokesman for the DoD's Joint Non-Lethal Weapons Program, the CWC prohibits some temporarily disabling compounds on the basis of whether they activate the trigeminal nerve when people are exposed to it - those that do are classed as riot-control agents (RCA). The nerve conveys sensation from the face, cheeks and jaw, but does not control smell.

"If a particular malodorant is disseminated with a concentration that does not activate the trigeminal nerve, it may not require designation as an RCA under the CWC," says Hughes.

Stink bombs do not cause injury, but the intense, unfamiliar foul smells affect the amygdala and trigger an unthinking fear reaction that causes the target to flee. This has led to a long history of Pentagon interest in malodorants, but little has come of it (New Scientist, 7 July 2001, p 42). Now, regardless of whether the loophole is real, the DoD is moving ahead with developing stink bombs.

Among them is the US Navy initiative for malodorant grenades, which can be thrown, or fired from a grenade launcher. The aim is to encapsulate the malodorant without leakage and deliver a payload that could clear a 5-metre-square room. Previous efforts have failed because the undisclosed compound involved is highly volatile.

The XM1063, a malodorant round for 155-millimetre artillery, is also waiting in the wings. This scatters stink bomblets over a wide area. The project is on hold, but has been developed by General Dynamics, a defence company based in West Falls Church, Virginia, to the stage of test firings and could be reactivated.

Julian Robinson, a chemical weapons researcher at the University of Sussex in Brighton, UK, is sceptical about the existence of the CWC loophole. He suggests that a malodorant might qualify as an RCA from the effects of the smell alone. He also says that it is not clear whether a malodorant would be classed as a toxic chemical under the CWC definition.

The Israel Defense Forces (IDF) - whose country is one of eight that are not party to the CWC - already use a persistent malodorant called Skunk. The IDF has used Skunk, typically sprayed from a vehicle-mounted water cannon, to disperse crowds in the Palestinian territories. Critics, however, accuse the IDF of using it excessively, coating houses in villages after protests as a form of collective punishment.

It remains to be seen whether malodorants will be effective for combat, or whether simple countermeasures, like gas masks, could neutralise them. But if the developers are successful, then in future war really will stink.

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