American troops no longer serve a purpose there. It is time to get out. Now.

The game is over in Afghanistan. An American presence can no longer serve any purpose. Or, rather, it can only extend and exacerbate the pathologies of this war. It is time to get out, and more quickly than President Obama had been planning. The consequences of leaving may be grim, but the consequences of staying are probably grimmer.

Sunday’s massacre in Kandahar province, in which a veteran U.S. Army staff sergeant sneaked out of his base at 3 a.m., strolled into a village, and methodically gunned down 16 Afghan civilians, including nine children, is but the latest sign of a massive unraveling.

Two weekends earlier, an Afghan gunman killed two U.S. officers inside the Interior Ministry’s headquarters (making the ninth and tenth Americans who have lost their lives this year at the hands of Afghans they’d been training). Shortly before then, violent riots broke out when Americans were discovered burning copies of the Quran. Just two days before the Kandahar rampage, NATO helicopters flying over Kapisa province, in eastern Afghanistan, fired on a group of civilians, killing four and injuring three, prompting large street protests.

Finally, the New York Times reported over the weekend that Afghan president Hamid Karzai is starting to enforce a law banning the use of private security guards to protect foreign business and aid workers, requiring that Afghan police be used instead. Even before the incident in Kandahar, Western officials were predicting that the new law would force a shutdown of nearly every development project; no civilians would want to stick around without someone reliable guarding their backs—and after the string of incidents, no Afghan can be regarded as reliable, any more than Afghans can regard any American as reliable.

And there’s the problem. The U.S. and NATO strategy in Afghanistan relies on building trust, and those bonds of trust—always tenuous at best—are now severed, perhaps irreparably.

Trust has been a centerpiece of the basic counterinsurgency strategy, which calls for NATO troops to focus on protecting the Afghan people, living among them, gaining intelligence from them on the insurgency, and helping to provide them basic services, in order to strengthen the ties between the people and their government, and thus to undermine their ties to the Taliban.

Trust has also been essential to the transition strategy, in which NATO troops train and gradually hand over authority to the Afghan army and police.

The counterinsurgency strategy falls apart if the Afghan people have to worry that an American soldier in their midst might come murder their family in the night. The transition strategy falls apart if NATO troops have to worry that an Afghan cop or soldier they’re training might, at any moment, shoot them in the back.

Some of this collapse might be contained if, say, a respected Afghan leader moved swiftly to tamp down the outrage. These recent killings of civilians or allies are, after all, in one sense, anomalies. The Quran burnings, bureaucratic incompetence; the helicopter shootings in Kapisa province, an accident of warfare; the Kandahar massacre, an isolated case of, apparently, a soldier gone haywire; even the shootings of the two U.S. officers at the Interior Ministry’s headquarters seem to have been motivated by unique circumstances.

But President Karzai is not highly respected among his people; if he were, he might not be facing such a strong, agile insurgency. And because he’s not very popular, he can’t risk losing further favor by standing up for foreign armies, especially now.