Less than 50 percent of so-called "green on blue" attacks are perpetrated by Taliban infiltrators into the Afghan army, the US and Nato Commander General John Allen said Sunday.
The shooting deaths of foreign soldiers by Afghan army personnel, or Afghans in army uniform, were found to not be the work of the Islamic militant group in more than half the cases, according to investigations, Allen said.
"It's important to note that in the analysis that we have done, less than 50 percent of the ones that have perpetrated these attacks were in fact Taliban infiltrators," Allen told reporters at a press briefing in Chicago.
"Many of these folks are self-radicalised. So it's important to understand and be able to recognise the nature of that self-radicalisation in the ranks."
Allen said that each single incident was important and investigated, with serious measures undertaken to prevent such attacks in coordination with Afghanistan's Ministry of Defense, Ministry of Interior and National Directorate of Security.
As a result, as many as 160 individuals planning to attack Isaf forces have been arrested in the last several months, Allen said.
The green on blue attacks have escalated this year, with already 22 foreign soldiers killed in 16 attacks in 2012. In last year's total, there were 35 foreign soldiers killed in 21 attacks, while in 2010 there were 20 soldiers killed in 11 attacks. These figures do not include attacks that did not lead to foreign troop fatalities.
Allen noted that the protection measures were taken "bilaterally, to protect each other".
"It's not well-known that the Afghans suffer nearly as many casualties from insider threats as we do," he said.
Responding to reporters' questions, Allen confirmed that the planned drawdown of 23,000 US troops will go ahead, with that number to return to the US by the end of September.
He said the surge tactic had achieved its aim, meaning those forces were no longer required.
"Part of the importance of the surge was to create conditions under which we could withdraw those troops - and I think those conditions are now underway - and that was to move the Afghan National Security forces to a level and to a confidence where they could begin to assume the role of some of those surge forces in the field," he said.
When asked about France's early withdrawal of troops from Afghanistan, Allen replied that it was a sovereign decision and to that effect he supports it, but it will not affect Isaf's mission in Afghanistan as Afghan forces are getting stronger and taking the responsibility.
"We have the capacity, using our current force structure to ensure that there is no degradation in security with respect to any decisions that might be made," Allen said.
Allen said the aim was for the Afghan National Security Forces (ANSF) to reach their full potential by the end of 2013 - a year Isaf has consequently termed "Milestone 2013".
"We will continue to train and equip and ultimately to field the entire ANSF by the end of 2013. So we'll be approaching a key crossover point in the campaign in 2013 - what's known as the Milestone 2013 - where the ANSF will move into security lead in the context of the counterinsurgency campaign and where Isaf forces will be supporting that move into the lead," he said.
The ANSF currently has about 330,000 troops and is expected to increase to 352,000 by the end of the year.
Regarding the reopening of the Nato supply route in Pakistan, Allen said that there are positive indications that about the reopening of the border and reiterated that it did not affect his mission in Afghanistan,
He also said he had positive negotiations with Pakistani Chief of Staff General Ashfaq Kayani in a trilateral meeting in Islamabad, but did not disclose details.