Afghan officer opens fire, kills 9 Americans

Those killed were trainers and advisers for the nascent Afghan air force. The shooting was the deadliest attack by a member of the Afghan security forces, or an insurgent impersonating them, on coalition troops or Afghan soldiers or policemen. There have been seven such attacks so far this year.

Although the individual circumstances may differ, the incidents of Afghans turning against their coalition partners seem to reflect growing anti-foreigner sentiment independent of the Taliban. Afghans are increasingly tired of the nearly decade-long war and think their lives have not improved despite billions of dollars in international aid.

The Taliban, who are currently staging their opening salvos of the spring fighting season, boasted that the gunman in Wednesday's airport attack was a militant impersonating an army officer.

This claim did not seem credible, however.

Defense Ministry spokesman Gen. Mohammad Zahir Azimi said the gunman was an officer who had served as a pilot in the Afghan military for the past 20 years. The gunman — identified as Ahmad Gul, 48, of Tarakhail district in Kabul province — died in an exchange of fire that followed his attack.