Leading article: Keep torturers out of UK airspace

Nothing destroyed the moral case for the US war in Vietnam quite so effectively as the complicity of American forces in the use of torture. Of the many lessons of that conflict which optimists hoped the US had learnt, this was surely one of the most important: that it is impossible to maintain the support of domestic opinion for military engagement abroad unless it is conducted by high ethical standards. Those who supported the overthrow of the Taliban in Afghanistan and even those who supported the invasion of Iraq are increasingly dismayed by the contempt of the Bush administration for this principle.

They had been warned. By this newspaper, but also by Vice-President Dick Cheney. Five days after 9/11 he described the US response in a television interview: "We also have to work the dark side, if you will. We've got to spend time in the shadows in the intelligence world. A lot of what needs to be done here will have to be done quietly, without any discussion."

The effect of those words on a regime that explicitly authorised "aggressive interrogation" techniques, including waterboarding, which involves bringing the victim to the point of death by drowning, does not have to be imagined. It has now been reported, extensively and authoritatively. The signal went out from the top that US forces would be expected to "work the dark side", with no questions asked. And there should be no doubt that responsibility lies right at the very top. As the combative Democratic consultant turned commentator James Carville pointed out: "Harry Truman did not say, 'The buck stops with the Vice-President.'"

Torture forfeits the high moral ground so essential to maintaining and/or winning popular consent, but it does not work. Confessions extracted by torture are unreliable, as Colin Powell - who presented duff evidence, apparently the result of torture, to the UN - can testify.

The responsibility of the British Government now is twofold. Having taken a while to wake up to this subject, it must condemn the use of torture in word and deed. To its credit, the British Army in Iraq has stopped the practice of hooding prisoners - one of the techniques permitted by the US. But the Foreign Secretary must condemn specific practices used by the Americans and say, as Chris Mullin argues on the opposite page, that US aircraft carrying detainees may not use this country as a stopover unless they are certified torture-free.