KABUL, Afghanistan — A spokesman for the International Security Assistance Force on Tuesday said there was no evidence of widespread infiltration of Afghan security forces by insurgents, and that it is too soon to say whether last week’s attack by an Afghan soldier on French troops was connected to the Taliban.

Investigations of previous green-on-blue incidents, in which Afghan soldiers and policemen knowingly turn a weapon on Western forces, turned up “a multitude of reasons” for the attacks, said German Brig. Gen. Carsten Jacobsen.

Friday’s shooting in Kapisa province left four French troops dead and 15 wounded.

“We know that the perpetrator was a member of the Afghan National Army, and he is in the custody of the Afghan National Army,” Jacobsen said.

An investigation into last year’s shooting at Kabul airport, which left nine Western trainers dead, took more than eight months to complete; a similar investigation into Friday’s incident is under way.

France has suspended training and joint combat operations with Afghan forces and threatened an early pullout of its troops.

“If France does not manage to find a solution with the Afghan authorities to ensure better security of the French soldiers, then we will seriously question our military presence in the country,” Col. Thierry Burkhard, a spokesman for France’s defense ministry, told CNN. “It is too early to speculate what actions would be taken.”

French Defense Minister Gerard Longuet was sent to Afghanistan to investigate the attacks and seek guarantees from Afghan authorities for the security of French trainers.

“The minister will return when he feels he has the information and assurances he is looking for,” Burkhard said.

According to a May 2011 report commissioned by U.S. forces in Afghanistan, cases of Afghan troops turning their weapons on foreigners “are no longer isolated.”

The report, titled “A crisis of trust and cultural incompatibility,” concluded that such green-on-blue murders “reflect a growing systemic threat.”

“Rather than just a result of insurgent infiltration into (Afghan National Security Forces), indicators exist that many of these fratricide incidents resulted from personal clashes,” Jeffrey Bordin, a behavioral scientist, wrote in the report’s summary.

Jacobsen said cultural understanding between Afghan and Western forces “is of high importance, and therefore naturally is part of the training of coalition soldiers before they are deployed.”

But while in Afghanistan, he said, the conduct of Western forces “is a question of leadership, and that is why we have to look into every single one of these cases to draw the right conclusions.”

Bordin’s report, which came out in May 2011, cited 26 green-on-blue attacks between May 2007 and May 2011 — roughly one incident every two months.

There have been at least four green-on-blue incidents in recent weeks, three of which resulted in the deaths of Western troops. Near the end of December, an Afghan soldier killed two French troops in Kapisa. Less than a week earlier, an Afghan soldier fired on U.S. troops in the western part of the country, but was gunned down before killing anyone.

Earlier this month, a soldier with the Alaska-based 1st Stryker Brigade Combat Team was killed and three others were wounded by an Afghan soldier while playing volleyball in Zabul province.

“It is an unfortunate truth that we have seen cases of green-on-blue over the years,” Jacobsen told reporters.

“But there are no indicators of systemic infiltration into Afghan national security forces,” he said. “Actually, this is something that we very carefully look at on a daily basis. As we’ve seen with incidents of this kind in the past, the reasons are always different, and there is a multitude of reasons when the investigations are completed.”

Because of the large number of recruits needed to grow the country’s forces to 352,000 by the end of the year from roughly 306,000 now, “the most important thing where improvements have to be made on a permanent basis is the vetting of young recruits,” he said.

The current vetting process “minimizes the chance of Taliban infiltration, but it does not stop individual mistakes, individual failures like probably the one we have seen last week.”

millhamm@estripes.osd.milTwitter: @mattmillham

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