NATO has ordered a cutback on operations alongside Afghan forces in response to a surge of "insider attacks" on foreign servicemen.
The move could complicate plans to hand security over to Afghan forces ahead of a 2014 drawdown.
The order indefinitely suspends joint operations for units smaller than 800-strong battalions, where most training and mentoring takes place.
NATO spokesman Major Adam Wojack said the order would impact on the "vast majority" of the 350,000 Afghan National Security Force members.
Meanwhile, an Afghan insurgent group has claimed responsibility for a suicide attack on a minibus that killed 12 people, including nine foreigners, near Kabul.
Hezb-e-Islami said the attack was launched in retaliation for a US made film mocking the Prophet Muhammad.
It said a woman wearing a suicide vest detonated the explosives.
The attack underscored growing anger in Afghanistan over the film, which has enraged much of the Muslim world.
It led to the killing of the US ambassador to Libya Christopher Stevens and three other Americans at the US consulate in Benghazi last week.
The leader of the Lebanese militant group Hezbollah has also denounced the anti-islamic film.
Speaking at a rally attended by thousands of people in the Lebanese capital Beirut, Hassan Nasrallah said the US faced very dangerous repercussions if it allows the full video to be released.
Thousands of protesters clashed with police in the Afghan capital yesterday, burning cars and throwing rocks at security forces.
The suicide attack was the first in Kabul involving a woman and the foreigners killed were mostly Russian and South African pilots working for an international courier company, senior police sources said.
The toll was the highest on foreigners in the city since last April when an Afghan air force pilot shot dead eight Americans after an argument at Kabul International Airport.