A recurring type of incident that has inflicted casualties on U.S. and other NATO forces in Afghanistan has been the shooting of coalition troops by Afghan army soldiers with whom they are supposed to be collaborating. I'm not talking about assaults by unknown individuals wearing army uniforms, who may be part of a Taliban operation in which purloined uniforms were used to get better access to the target. I am referring instead to incidents in which the attackers were undeniably government soldiers, manning the same outpost or base as the coalition troops who became their victims. Such incidents so far have accounted for only a small number of NATO casualties, but they are an especially distressing way to incur any casualty at all. They constitute a discouraging statement about lack of trust between allies and about the extent of resentment from coalition operations.

The incidents also reflect a larger and longer-standing pattern within Afghanistan, in which loyalties often are little more than skin-deep. Throughout the different phases of the long-running Afghan civil war, stretching back to when the Soviets were fighting there, changing alliances and switching sides have been common. Often entire militias rather than just individual fighters have done the switching. The allegiances of the moment reflect deals that have been struck, as well as resentments or debts that have been incurred.

This means that the timetables for expanding Afghan government forces and turning over security responsibilities to them have a fragile and almost artificial quality. Much as we would like to think of this process as irreversible, in which the government forces will be providers of stability and order as staunch as the coalition forces they replace, it is not. Afghans, including ones wearing a uniform, will continue to shift allegiances according to the politics and deals of the day. And this will be true no matter how long the timetable lasts and when it is that coalition forces come home.