NATO Secretary General Anders Fogh Rasmussen has expressed his \"shock and sadness\" at the killing of 16 Afghan civilians by an American soldier in Kandahar on Sunday. \"I offer my heartfelt condolences and sympathy to their families and loved ones, and to the Afghan people and government,\" he said in a statement. Rasmussen said he fully supports the commitment by General John Allen, Commander of International Security Assistance Force (ISAF) in Afghanistan to establish the facts and hold anyone responsible to account. \"We remain firmly committed to our mission of building a strong and stable Afghanistan, together with our Afghan partners,\" he added.