Rod Nordland

KABUL, AFGHANISTAN: The toll in a wave of attacks against coalition forces by their Afghan counterparts rose this week, underscoring the increasing tempo of the so-called green-on-blue assaults this year.

Details have emerged about two such cases that occurred Wednesday. In one, NATO and Afghan officials Friday confirmed that two Afghan policemen opened fire on coalition troops in Zhare District, near the city of Kandahar, wounding two NATO soldiers before they were themselves killed.

In the other — in which a coalition soldier was killed in Kandahar province by a man in an Afghan soldier’s uniform — a California news organization identified the victim as Andrew Britton, 25, a Green Beret whose identity and death were confirmed by a family friend in Simi Valley.

So far this year, there have been 11 attacks by Afghan security forces against coalition soldiers, resulting in the deaths of 18 people, 10 of them Americans, according to a spokesman for the NATO-led International Security Assistance Force in Afghanistan, Jamie Graybeal.

That is 20 percent of the total of NATO combat fatalities so far this year.

By comparison, in 2011 there were 21 such attacks leading to 35 deaths, he said. Last year a classified study commissioned by the U.S. military found that 58 U.S. combat fatalities — 6 percent — came in 26 green-on-blue attacks between May 2007 and May 2011.

The attacks come in the context of a series of incendiary events, including an inadvertent Quran burning in February that led to widespread violence; a rampage by a U.S. soldier in Kandahar province, in which 16 or 17 civilians were massacred; and the desecration of what were identified as the corpses of Taliban fighters, once in January and again in April.

In Washington recently, the Afghan defense minister, Abdul Rahim Wardak, told reporters that his government was taking measures to prevent green-on-blue attacks.

“We are doing much better vetting in our recruiting centers, requiring two individuals as guarantors for every applicant and are doing full background checks on all of our soldiers,” he said.

In the case of the Green Beret, the police chief in Shah Wali Kot district in Kandahar province, Pacha Khan, was quoted by Agence France-Presse as saying that the American was killed along with two Afghan troops and an interpreter in a night raid gone awry.

“Probably Afghan and U.S. forces had an argument that triggered the incident,” Khan was quoted as saying.

He said that an Afghan special forces soldier shot the U.S. soldier and his interpreter, and that return fire killed the two Afghan soldiers.