Mass killing of Afghan civilians by US soldier, like the backlash against the Qur'an-burning, displays the fragility of this conflict
The mass killing of Afghan civilians by a US soldier in Kandahar was a shocking reminder of an enduring truth of this decade-old conflict: the efforts of thousands of people over many years at a cost of billions can be undone in a few seconds by the actions of a single, hate-addled individual.
It is a truth that cuts both ways. The increasingly frequent murder of Nato trainers by the Afghans they are supposed to mentor has done as much to eradicate trust in the relationship between the Kabul government and its western backers as the sight of US marines videoed while urinating on the corpses of insurgents, or the mindless decision to burn Qur'ans at a US military base.
Six American soldiers were killed in the furious backlash to the Qur'an-burning, bringing the number of Nato trainers killed in the past five years to 75 at least. Two of those killed in the latest bout of bloodletting were high-ranking officers serving as advisers at the ministry of the interior. They were found on 25 February, shot in the back of the head in their offices at the tightly guarded ministry headquarters. All military advisers were immediately withdrawn and are unlikely to return to their posts without body armour and armed escorts.
Even such a tentative return is likely to be delayed in the face of a new wave of popular anger as the news spreads that nine children and three women were among the victims of Sunday's indiscriminate killings.
The US embassy in Kabul speedily issued condolence statements in Pashtu, Dari and English, assuring the Afghan people that "the individual or individuals responsible for this act will be identified and brought to justice", but they are likely to do little to stop the spread of conspiracy theories implicating the Americans and their allies in a plot against the nation. Few Afghans believe that the burning of Qur'ans in February was an anomaly. Amid rising tensions, it felt to many like a calculated insult, and probably did more to fuel the insurgency than 100 Taliban attacks.
Consequently, what seemed a just-about plausible strategy a few months ago now looks almost futile. The US and its allies in the International Security Assistance Force had planned to withdraw from combat duties over the next two years, to take up a "train and advise" role, alongside narrowly focused counter-terrorist operations aimed at eradicating any resurgence of al-Qaida.
The enormous deficit of trust in Afghanistan that feeds on itself and grows with every passing day raises serious questions over whether such a "train and advise" strategy is feasible. Meanwhile, the lack of a strategic partnership agreement between the US and Afghanistan jeopardises any future counter-terrorism mission. A deal has been fudged by Washington and Kabul on the issue of custody of Afghan detainees, but not on the even more vexed issue of US-led night raids on villages suspected of being insurgent strongholds. As for the matter of future US bases in Afghanistan, Karzai said on Sunday that a decision would be put off until next year.
Such is the bleak reality facing Barack Obama and David Cameron when they sit down in Washington to discuss Afghanistan on Monday. The shared narrative they have presented to their nations on how the Afghan war will end has been relentlessly eroded by the death toll among their soldiers and the daily headlines about the Karzai government's seemingly incorrigible venality, like the Wall Street Journal report over the weekend that the US-funded Afghan air force was using its planes to smuggle narcotics and illegal weapons around the country.
Support for the war is haemorrhaging rapidly in the US and the UK. Commentators in both countries question whether the continued presence of western troops, at great cost in lives and scarce resources, will do Afghanistan any good.
In fact, there are few government strategists in Washington, London or Paris who expect the situation to get any better. The issue now, and in the runup to the Nato summit in Chicago in May, is how the post-surge western involvement in Afghanistan can prevent the situation from getting incalculably worse. Handing over security to Kabul without triggering an all-out civil war, with casualties measured in the tens or hundreds of thousands, would right now count as a success.