The Taliban are involved in a quarter of Afghan security personnel attacks on NATO colleagues, according to a military commander.
The surge of assaults, unprecedented in modern warfare, have seen Afghan troops opening fire on their NATO colleagues more than 30 times this year, killing at least 45 foreign troops -- most of them Americans.
US Lieutenant General James Terry, head of the NATO-led coalition's joint command in Afghanistan, said about 25 to 26 percent of the attacks were "insurgent-related".
In an overnight briefing to reporters in Washington via video link from Afghanistan, he said 10 percent of attacks are "directly connected" to insurgents and classified 15 percent as "insurgent-associated".
"In other words, there's some indication there as soldiers commit the offences, they escape from the area. There's some insurgent facilitation that -- that helps them. So that's where you get the 25 percent from, and that's the insurgent involvement."
He said officials did not know the exact cause of the remaining attacks, but estimated another 25 percent were "personal", which he admitted could be eased by greater understanding of cultural sensitivities.
"I would just say that what we all recognize is that this is a society that's really been traumatised by 30-plus years of war," he said.
"And we also understand that a lot of grievances and dispute resolutions are done, frankly, at the barrel of a gun out there."
Afghanistan said Wednesday it had arrested or sacked hundreds of Afghan soldiers in a bid to stem a trend that threatens to undermine Western plans for a troop withdrawal.
Terry said he heard 200-300 Afghan troops were removed from the force but was waiting to learn precise numbers and details from Afghan defence officials.