Story highlights

NEW: A U.S. House committee will meet Wednesday about an attack on U.S. personnel

The death is the latest instance of "green on blue" killings

Pentagon: "We believe that they do appear to be increasing in frequency in recent months"

NATO says such incidents are isolated, as thousands of Afghan and coalition troops work together

Kabul, Afghanistan CNN  — 

A man in an Afghan National Army uniform killed a NATO service member in southern Afghanistan, once again bringing a disturbing issue to center stage in the long Asian war – attacks by local security forces against coalition troops.

The incident took place Tuesday when the man “turned his weapon against an International Security Assistance Force service member,” an ISAF statement said.

Per policy, the alliance did not release the victim’s identity or nationality.

“Green on blue” – a euphemism for attacks by members of the Afghan security forces on their allies in the international force – are a mere fraction of the total coalition deaths in the war.

But they may feed a climate of uncertainty and even mutual suspicion between Afghan units and their coalition partners at a time when ISAF is trying to hand over control of more districts and provinces to the Afghan National Army, analysts say.

“We believe that they do appear to be increasing in frequency in recent months,” Pentagon spokesman John Kirby told reporters in January. “We’ve seen the numbers increase in recent months, certainly.”

The U.S. House Armed Services Committee will hear testimony Wednesday about the attack on U.S. personnel at the Frontenac base in Afghanistan last March.

In January, an Afghan soldier killed four French troops, prompting French President Nicolas Sarkozy to suspend its training operations and combat help.

In December, another Afghan soldier killed two French soldiers serving in an engineers’ regiment.

“The French army is not in Afghanistan to be shot at by Afghan soldiers,” Sarkozy said after the January shooting.

Last year, an Afghan air force officer killed eight American airmen and a security contractor.

The Afghan air force officer, Ahmed Gul, had declared his desire to kill Americans, behaved erratically at work and frequented a mosque known for its anti-American views, according to a U.S. Air Force investigation into the incident.

A NATO analysis last year found 52 U.S. and allied soldiers had been killed in “green on blue” attacks between 2005 and June of 2011.

And while the numbers raise fears that the Taliban are infiltrating the Afghan National Army and police force, military analysts and intelligence officials say the reality is more complicated.

The analysis concludes that combat stress provoked 36% of the attacks, even if the Taliban subsequently claimed responsibility.

In 23% of the cases, an Afghan soldier had been persuaded by the Taliban to carry out an attack – but the motive in an additional 32% of cases was unknown.

“Such tragic incidents are terrible and grab headlines, but they are isolated,” NATO Secretary General Anders Fogh Rasmussen said last month. “The reality is that every day, 130,000 ISAF troops from 50 nations fight and train with over 300,000 Afghan soldiers. That takes a lot of trust among a lot of soldiers.”