U.S. Secretary of State Hillary Clinton condemned an attack by an American soldier who reportedly killed 16 Afghan villagers on Sunday.

(SOUNDBITE) (English) U.S. SECRETARY OF STATE HILLARY CLINTON, SAYING:

"Like many other Americans, I was shocked and saddened by the killings of innocent Afghan villagers this weekend. We send our condolences to families who have lost their loved ones and to the people of Afghanistan. This is not who we are. The United States is committed to seeing that those responsible will be held accountable."

Just days before Sunday's attack, Kabul and Washington had made significant progress in negotiations on a Strategic Partnership Agreement that would allow American advisers and special forces to stay in Afghanistan after foreign combat troops leave at the end of 2014.

But securing a deal may be far more difficult now after the shooting spree in Kandahar which killed mostly women and children.

Anti-Americanism in Afghanistan boiled over last month after copies of the the Koran, were inadvertently burned at a NATO base. The carnage in Kandahar is likely to further fan those sentiments.

Deborah Lutterbeck, Reuters.