The attack occurred in Khost, a province that borders Pakistan. A police spokesman, Wazir Pacha, said the attack was carried out by a suicide bomber in a vehicle. The NATO spokesman, though, blamed the attack on a roadside bomb.
The majority of NATO troops in Khost are American, though the spokesman for NATO's International Security Assistance Force would not confirm the troops' nationality. The spokesman asked not to be identified because he was not the media office's lead spokesman.
U.S. Military leaders have said they plan to send up to 30,000 more troops into the country over the next year to reinforce the 33,000 American forces already in the country.