THE world is waiting to see whether or not Saddam Hussein will use chemical weapons against the troops invading Iraq. But it is the US that is in danger of breaching the 1997 Chemical Weapons Convention.

At issue is the use of "non-lethal" riot-control agents such as tear gas and pepper spray, which the US military has allegedly taken to the Gulf. According to some experts, this act alone could be interpreted as "military preparations to use chemical weapons", specifically prohibited by the convention.

Under the convention, which the US and Britain have signed but Iraq has not, the legal status of riot-control agents depends on their intended use. Deploying them to enforce laws, such as controlling a riot by your own civilians, is expressly permitted. But the convention specifically rules out their use in warfare: for example, to flush enemy soldiers out of bunkers so they can be shot, ...