Letter: Sudan `nerve gas'

Sir: It may help your readers to weigh up the evidence relating to the suggestion by the US that a Sudanese factory was engaged in assisting the production of the nerve poison VX to know more facts now that the chemical linked to nerve warfare has been definitively described by US officials as O-ethyl methyl phosphonothioic acid (EMPTA) ("US strives to justify air strike on Sudan", 26 August).

EMPTA is not itself a nerve poison to be used in warfare. It could be a degradation product or an intermediate in the preparation of VX. However, it could also be linked to quite other synthetic chemical compounds. Insect and nematode (worm) agricultural chemicals are not unrelated. Nerve poisons are used against such "biological enemies".

To justify a missile attack on a sovereign state the USA (and now the UK) must give weightier evidence than the finding of (trace?) amounts of this chemical (in soils?). It is critical therefore that we know where this compound was found, in what quantity it is known to have been produced and that there was a link to nerve-gas production.

No matter how much our government dislikes a group of people, or even suspects it of murderous intent, we must not be misled by technical language to cover up speculation. The UN or the Hague Court must ask the US and now the UK to say clearly what information provoked the attack on Sudan. If we want law and order to prevail we must show that we have just cause for such action, otherwise we are approving terrorist methods of our own. Like the overwhelming majority of people I am against all forms of terrorism.

Professor R J P WILLIAMS FRS

Inorganic Chemistry Laboratory

University of Oxford