Rupert Cornwell: Poisonous atmosphere adds to growing mistrust of American troops

President Obama today vowed to “follow the facts wherever they lead” in the massacre of Afghan villagers allegedly carried out by a rogue American soldier, whose trial and punishment could now transform the politics of the 11-year war, both in Afghanistan and the US.

Almost every personal detail, bar his name, is known about the suspect. He is a married 38-year-old staff sergeant with two children who joined the army in 2001 and was deployed to Afghanistan last December. Previously, he had served three tours of duty in Iraq, where he reportedly suffered a serious brain injury in a 2010 vehicle accident.

The suspect is currently in detention at a military facility in Kandahar, as US investigators try to work out what led him to slip away from his combat post, slaughter 16 people, including women and children as they slept in the early hours of Sunday, and then turn himself in after his killing spree. His wife and children meanwhile have been brought for their own safety into his unit’s home base outside Tacoma in Washington state.

Earlier, as suggestions multiplied that he might be suffering from post-traumatic stress disorder, it was not clear what charges would be brought against him and when. Only at that point will the staff sergeant’s identity be made public. According to Leon Panetta, the Defence Secretary, he could face capital charges, if deemed fit to face trial.

But neither that possibility, nor Mr Obama’s own pledge to treat the case “as seriously as if our own citizens and children had been murdered”, may be enough to satisfy the Afghan government and public. For them, the outrage is but the latest in a series of incidents to undermine trust in the US and the some 90,000 American troops still deployed in the country.

Despite US insistence that a lone individual was responsible for the rampage, some Afghans believe that at least two soldiers were involved. Demands are mounting in Kabul for an open trial of the suspect, on Afghan soil. But that almost certainly will not happen. Officials in Washington promise the most thorough and transparent investigation possible, but existing agreements stipulate he will be tried before a US military court, to which Afghans are likely to have only limited access.

Thus far at least, the massacre has not provoked violence on the scale that followed the burning of Korans and other Islamic texts in a dump pit last month, when 30 people died in protests, and six US servicemen were killed by Afghan colleagues, their supposed friends. However, the Taliban today weighed in, threatening to behead any American who fell into their hands.

The biggest repercussions however could be military and political. Speaking at the White House, Mr Obama made clear he intends to stick to existing plans to “responsibly wind down this war,” with the removal of a further 23,000 US troops from Afghanistan by the end of summer, following the 10,000 withdrawn last year. The last combat troops are due to leave by 2014, by which time Afghans will have taken charge of their own security. But the poisonous atmosphere could make it even harder to negotiate post-2014 arrangements for US troops to stay on as trainers and supervisors.

At home, Sunday’s killing spree has fuelled demands for a speedier end to an ever more unpopular war whose prime purpose, many argue, was achieved last May when Osama bin Laden was found and killed. Out on the campaign trail, hitherto hawkish Republican presidential candidates are starting to suggest that US troops should be pulled out sooner than the Obama administration currently plans.