Five American troops killed in Afghanistan friendly fire

Five American troops were killed by a U.S. airstrike called in to help them after they were ambushed by the Taliban in southern Afghanistan, in one of the deadliest friendly fire incidents in nearly 14 years of war, officials said Tuesday.

Pentagon spokesman Rear Adm. John Kirby said the five servicemen were killed Monday "during a security operation in southern Afghanistan."

"Investigators are looking into the likelihood that friendly fire was the cause. Our thoughts and prayers are with the families of these fallen," Kirby said in a statement.

In Washington, U.S. defense officials said the five Americans were with a NATO special operations unit that they did not identify. Earlier, officials had said all five were special operations-qualified troops, but later an official said their exact affiliation was unclear and one or more may have been a conventional soldier working with the special operations unit.

Al Jazeera’s Kabul bureau reported U.S. and Afghan forces were conducting a ground operation in the area's Arghandab district early Monday before they were ambushed by the Taliban. The troops called for air support, who then opened fire, killing the five U.S. troops, their local interpreter and one Afghan soldier.

The deaths were a fresh reminder that the conflict is not over for some U.S. troops, who will keep fighting for at least two more years. Most of the forces operating in the area where the five U.S. soldiers were killed are from the United States.

The attack is one of the most serious cases involving friendly fire during the nearly 14-year Afghan war. One of the worst came in April 2002 when four Canadian soldiers were killed when an American F-16 dropped a bomb on them near a night firing exercise in southern Kandahar.

The deaths bring the number of NATO soldiers killed so far this year in Afghanistan to 36, with eight service members killed in June. Casualties have been falling in the U.S.-led military coalition as its forces pull back to allow the Afghan army and police to fight the Taliban.

Airstrikes that kill NATO coalition soldiers are far less common than those that accidentally kill Afghan civilians — incidents that have long caused tensions between the Afghan government and coalition forces.

Al Jazeera and The Associated Press