As such attacks mounted this year, U.S. officials in Kabul and Washington insisted they were "isolated incidents" and withheld details. An AP investigation earlier this month showed that at least 63 coalition troops — mostly Americans — had been killed and more than 85 wounded in at least 46 insider attacks. That's an average of nearly one attack a week. In 2011, 21 insider attacks killed 35 coalition troops.
There have also been incidents of Taliban and other militants dressing in Afghan army and police uniforms to infiltrate NATO installations and attack foreigners.
In February, two U.S. soldiers — Lt. Col. John D. Loftis and Maj. Robert J. Marchanti, died from wounds received during an attack by an Afghan policeman at the Interior Ministry in Kabul. The incident forced NATO to temporarily pull out their advisers from a number of ministries and police units and revise procedures in dealing with Afghan counterparts.
The latest known insider attack took place Nov. 11 when a British soldier, Capt. Walter Reid Barrie, was killed by an Afghan army soldier during a football match between British and Afghan soldiers in the restive southern province of Helmand.
More than 50 Afghan members of the government's security forces also have died this year in attacks by their own colleagues. Taliban militants claim such attacks reflect a growing popular opposition to both foreign military presence and the Kabul government.
In Sunday's attack, Jawzjani, the provincial official, said the attacker was an Afghan policeman manning a checkpoint in Dirzab District who turned his weapon on five colleagues before fleeing to the militant Islamist group.