Pentagon Chief: Soldier Killing Reminder of Afghan Dangers

U.S. Defense Secretary Ashton Carter said Thursday the killing of an American soldier during an insider attack in Afghanistan showed that work remains to shore up Afghan forces in the "dangerous" country.

The U.S. soldier died when an Afghan army fighter Wednesday opened fire on an American delegation outside the governor's compound in Jalalabad, the capital of the militant-infested province of Nangarhar.

"I don't know all the circumstances of that incident, yet it's possible it's a 'green on blue' incident of the kind we've had before," Carter said, referring to insider attacks by Afghan troops on their NATO partners.

"The main thing obviously on my mind is the service members and their families. It's a reminder Afghanistan is still a dangerous place," he said shortly before leaving Tokyo for Seoul.

"There is still work to be done to support the Afghan security forces so that they can sustain the progress we've made in the last few years."

Wednesday's incident was the first such attack since Washington announced a delay in troop withdrawals from Afghanistan, responding to a request from Afghan President Ashraf Ghani. 

Most NATO combat troops withdrew from Afghanistan last year but a small contingent remains, including about 10,000 U.S. forces.

The U.S. Army soldier was part of a unit devoted to training and advising Afghan forces, officials told AFP.

U.S. troops returned fire, killing the gunman and wounding two other Afghan soldiers, local police said.