But the killing of two high-ranking NATO officers by an Afghan security official — and the subsequent decision by the top NATO commander in the country to recall his personnel from top Afghan ministries — has spurred doubts about whether Afghan security forces can be relied upon to provide for the protection of their Western partners. The consequences of that erosion of confidence, former U.S. officials and analysts say, could be devastating.
“If the trust, ability and willingness to partner falls apart, you are looking at the endgame here,” said Mark Jacobson, who served until last summer as the NATO deputy senior civilian representative in Kabul.
The killing of the U.S. officers on Saturday occurred two days after a man wearing an Afghan army uniform fatally shot two American troops in eastern Afghanistan, the latest in a string of incidents in recent months in which local security forces have turned against NATO personnel.
Some of the killings have been perpetrated by Afghan troops whose loyalties lay with the Taliban. But, in most cases, the attacks have been the result of tensions between U.S. forces and Afghans who felt as though they had suffered an insult to themselves or their faith.
On Sunday, Afghan President Hamid Karzai, who initially responded to the Koran burnings with outrage, sought to stem the latest wave of violence by issuing a plea for calm and blessing the withdrawal of NATO advisers from his ministries as a justifiable measure.
But protests continued, including in the northern city of Kunduz, where Afghan demonstrators opened fire and tossed a grenade at a U.S. base, wounding seven American troops. The Afghan defense and interior ministers canceled a long-planned trip to Washington to focus on curbing the violence, which has claimed 25 Afghan lives.
“We remain committed to a partnership with the Afghan government and people,” the U.S. ambassador to Kabul, Ryan C. Crocker, told CNN on Sunday, promising that American service members and civilians would continue to work with their Afghan allies.
For now, though, much of the cooperation between U.S. advisers and their Afghan partners is on hold. And even though the decision to withdraw the advisers is probably temporary, it is not clear how U.S. troops will be able to reestablish trust with Afghan security forces.
“This is not going back to business as usual,” an Army officer who works as an adviser in Kabul said Sunday. “The threat is still higher than normal.”
Once advisers return to the ministries, the officer said, some will probably have to shorten their visits, instead of remaining there for six- to 10-hour shifts, to reduce risks.
Senior Obama administration officials have sought to reassure a war-weary American public that the NATO combat mission in Afghanistan would draw to a close by the middle of next year. These officials have implied that the change to an advisory mission would not only mean fewer U.S. service members in Afghanistan, but also less risk for the noncombat troops who remain behind.
Military experts, however, say that the smaller U.S. advisory force might be more exposed to fratricidal attacks than conventional military units. Such attacks — which were exceptionally rare in Iraq — often stem from a cultural chasm between U.S. and Afghan troops.
Carter Malkasian, who served as a State Department adviser in southern Afghanistan’s Helmand province in 2010 and 2011, said one way to mitigate that risk is for advisers to build closer relationships with their Afghan partners. But the risk will always be there.
“The most effective advisers will be with their Afghans all the time, and that certainly does involve additional risk,” Malkasian said.
Unlike a typical infantry platoon, which consists of more than 35 heavily armed soldiers, the advisers work in teams of as few as a dozen troops. Some military and civilian advisers working in Afghanistan said Sunday that the risks associated with their jobs were still manageable and that they believed that they would soon be able to return to their work.
“I hope [the ban] is lifted soon,” said a State Department adviser working at a remote outpost in eastern Afghanistan. “Maybe I am complacent. I know we face all kinds of threats, but we have a job to do.”
Current plans call for the U.S. force in Afghanistan to fall from a peak of 100,000 troops to about 68,000 by the end of the summer. Further reductions are likely later this year and in 2013. All NATO combat troops are expected to be withdrawn by the end of 2014.
In an article in the upcoming issue of Foreign Affairs, Malkasian and Kael Weston, who served a multiyear stint as an adviser in southern Afghanistan, estimated that NATO could hold off the Taliban and keep the Afghan government and security forces functioning with as few as 25,000 advisory troops.
The Afghans would rely on the NATO advisers to call in airstrikes if their position was about to be overrun by a larger Taliban force. The advisers would ensure that their Afghan partner units were receiving ammunition, food and fuel from their headquarters. The Westerners also would help control the most damaging and overt acts of corruption.
To be effective, these troops would have to live without large American bases, expensive dining facilities and intensive quick-reaction forces.
“The more willing advisers are to accept risk,” Malkasian said, “the more effective they will be.”
Special correspondent Javed Hamdard in Kabul contributed to this report.