US contractors killed in apparent 'insider attack'

Three American contractors were killed and a fourth wounded when an Afghan soldier opened fire on them in the military airport in the Afghan capital of Kabul on Thursday, officials said.

The international force in Afghanistan also confirmed the shooting, which has been deemed an "insider attack."

"It is unclear yet why he shot these advisers and no one else was there to tell us the reason," an Afghan air force official who asked not to be named told Reuters news agency. "An investigation has been opened," the official added.

A US Defense Department official, who spoke on condition of anonymity, said the details of the attack remain unclear.

Mutual mistrust

Attacks by Afghan security forces on international troops, referred to as "green on blue" attacks, have served to foster mutual mistrust. The Pentagon warned in a 2014 report that such attacks may have "strategic effects on the campaign and could jeopardize the relationship" between coalition troops and Afghan security forces.

In an attack on August 5, US Major General Harold Greene was killed and a further 14 soldiers wounded when an apparent member of the Afghan security forces opened fire on international coalition forces at a military base west of Kabul.

The number of "green on blue" attacks peaked in 2012, with more than 40 attacks by Afghan security forces on coalition troops. There have been nearly 90 such attacks since 2008, though the number of attacks dropped significantly last year.

Violence continues to plague the war-ravaged country. At least 16 people were killed and a further 39 wounded Thursday when a suicide bomber detonated explosives at a funeral ceremony in the provincial capital of Mihtarlam, in eastern Afghanistan.

NATO's International Security Assistance Force (ISAF) recently ended its 13-year combat mission in the country. A small contingent of 12,000 mainly US troops is leading the new mission, "Resolute Support," which is to focus primarily on training and advising Afghan security forces.

Nearly 3,500 foreign troops have been killed in Afghanistan since fighting began in 2001. Around 5,000 Afghan security personnel were killed in 2014, 3,200 of them policemen.

bw/mg (AP, AFP, Reuters)