A US soldier accused of shooting dead 16 Afghan civilians has been flown out of Afghanistan, officials said, as Washington attempted to calm seething anger over a massacre that raised serious questions about the West’s war strategy.

Underscoring the instability in Afghanistan, an Afghan man in a stolen pickup truck sped onto the tarmac as a plane carrying US Defence Secretary Leon Panetta was about to land on Wednesday, an extraordinary security breach in a southern province next to where Sunday’s massacre took place.

No one on board the military plane carrying Panetta was hurt when it landed at a British base in Helmand province. Defence officials played down the incident, saying the Pentagon chief was never in danger. The pickup truck crashed into a ditch after it sped across the runway ramp and the driver, whose motives were unclear, emerged from the vehicle in flames.

He was being treated for burns, a Pentagon spokesman said, and a member of the NATO-led coalition was also hurt when the vehicle was stolen.

Panetta arrived for his unannounced visit three days after the massacre in neighbouring Kandahar province. Although Panetta’s trip was planned before the shooting, it comes as Afghan civilians and lawmakers alike demand answers.

Foremost among those demands is that the soldier responsible be tried in Afghanistan over the shooting, one of the worst of its kind since US-backed Afghan forces toppled the Taliban in 2001 for harbouring the al Qaeda masterminds of the Sept. 11 attacks on the United States.

Despite those calls, the US staff sergeant who gave himself up after the villagers, including nine children and three women, were killed has been flown out of Afghanistan, the Pentagon said on Wednesday.

US news outlets have reported that the sergeant had been taken there. The commander of US and Afghan forces in Afghanistan, General John Allen, made the decision based on a legal recommendation, a US official said.

Afghan President Hamid Karzai’s office was understood to have accepted that the soldier be tried in a US court, provided the process was transparent and open to media.