AP

BALANDI AN American soldier opened fire on villagers near his base in southern Afghanistan on Sunday and killed 16 civilians, according to President Hamid Karzai who called it an “assassination” and furiously demanded an explanation from Washington. Nine children and three women were among the dead.

“This is an assassination, an intentional killing of innocent civilians and cannot be forgiven,” Karzai said in a statement. He said he has repeatedly demanded the US stop killing Afghan civilians.

The violence over the Holy Quran burnings spurred calls in the US for a faster exit strategy from the 10-year-old Afghan war.

President Barack Obama even said recently that “now is the time for us to transition.” But he also said he had no plan to change the current timetable that has Afghans taking control of security countrywide by the end of 2014.

The tensions between the two countries had appeared to be easing as recently as Friday, when the US and Afghan governments signed a memorandum of understanding about the transfer of Afghan detainees to Afghan control, a key step towards an eventual strategic partnership to govern US forces in the country.

But Sunday’s shooting could push that agreement further away. “This is a fatal hammer blow on the US military mission in Afghanistan. Whatever sliver of trust and credibility we might have had following the burnings of the Holy Quran is now gone,” said David Cortright, the director of policy studies at Notre Dame’s Kroc Institute for International Peace Studies and an advocate for a quick withdrawal from Afghanistan.

“This may have been the act of a lone, deranged soldier. But the people of Afghanistan will see it for what it was, a wanton massacre of innocent civilians,” Cortright said.

Some villagers questioned whether a single soldier could have killed so many people. But a US official in Washington said the soldier, an Army staff sergeant, was believed to have acted alone and that initial reports indicated he returned to the base after the shooting and turned himself in.

Five people were wounded in the pre-dawn attack in Kandahar province, including a 15-year-old boy named Rafiullah who was shot in the leg and spoke to the president over the telephone. He described how the American soldier entered his house in the middle of the night, woke up his family and began shooting them.