The U.S. military has suspended the bulk of joint field operations with Afghan troops amid a wave of so-called insider attacks and concern about protests over an anti-Islam film.
Fox News has learned that while U.S. troops are still patrolling, as are the Afghans, the two sides are not running operations together for the time being without special approval.
Until now, U.S. and NATO troops routinely conducted operations with their Afghan counterparts. But under the new order, such operations will now require the approval of a regional commander. Fox News was told the step is a temporary measure.
The move comes after Afghan police on Sunday killed four American soldiers, and a gunman in an Afghan militia uniform shot dead two British soldiers a day earlier. It also comes in the wake of the week-long wave of protests across the Muslim world over an anti-Islam film.
NATO's International Security Assistance Force put out a statement stressing that ISAF took "some prudent, but temporary, measures to reduce our profile and vulnerability to civil disturbances or insider attacks" in response to the protests.
"This means that in some local instances, operational tempo has been reduced, or force protection has been increased. These actions balance the tension of the recent video with force protection, while maintaining the momentum of the campaign," the statement said.
ISAF stressed that NATO forces are "absolutely committed to partnering with, training, advising and assisting" Afghan forces.
But the move underscores the sustained trust problems NATO forces have had in preparing the Afghan security force to eventually take over.
U.S. Defense Secretary Leon Panetta said Tuesday the U.S. is concerned about the impact insider attacks are having on its forces in Afghanistan.
But he insisted Gen. John Allen, the top U.S. commander there, is taking necessary steps to protect the force while still ensuring the U.S. will be able to hand over security to the Afghans and be able to withdraw by the end of 2014.
He said the attacks do not mean the Taliban are succeeding. Instead, he said the Taliban "are resorting to efforts that try to strike at our force, try to create chaos, but do not in any way result in their regaining territory that has been lost."
Panetta spoke during a press conference in Beijing with China's minister of national defense, Gen. Liang Guanglie.
Early Tuesday, a suicide bomber rammed a car packed with explosives into a minibus carrying foreign aviation workers to the airport in the Afghan capital, Kabul, killing at least nine people. The Islamist militant group Hizb-i-Islami claimed responsibility for the dawn attack, saying it was revenge for the anti-Islam video.
So far this year, 51 international troops have been killed by Afghan forces or militants wearing their uniforms. The attacks have spiked in recent months, damaging the trust between the NATO and Afghan forces at a time when ongoing training and cooperation are critical in order for allied troops to leave Afghanistan by the end of 2014 and turn control of security over to the Afghan forces.
Fox News' Jennifer Griffin and Justin Fishel and The Associated Press contributed to this report.