As Americans and other Nato troops approach the 2014 target for their withdrawal from Afghanistan, the situation only seems to worsen. This is not an argument to prolong their stay but, on the contrary, to hasten their departure. The occupation is now only aggravating the country's fundamental instability.

On Sunday, in a brutal incident about which we are still learning the details, a US staff sergeant killed at least 16 civilians, including nine children and three women, in their homes near a military base in southern Kandahar. It was the worst attack on civilians, apart from air strikes, in the 11 years since the US entered Afghanistan.

This may be the isolated act of an unhinged madman, but it cannot help but have broader consequences. It may still be argued that the US war effort is meant to benefit Afghans; it is, however, incontrovertible that "people are running out of patience over the ignorance of foreign forces", as the Afghan parliament said in a statement yesterday.

The longer the US troops remain in the country, the more tension their presence is breeding. The burning of the Quran last month at Bagram Airbase, which triggered riots that have killed dozens, showed that even after more than a decade of war, US forces continue to thoroughly misunderstand the country, not to mention Muslims worldwide.

Sunday's deliberate murders, apparently by a rogue psychopath, are a reminder of atrocities in Iraq such as the Haditha massacre. There are some acts that are never forgotten and, whether a product of deliberate policy or not, will always stain US credibility after these ill-conceived wars.

At the same time, it would be wrong to blame all of Afghanistan's ills on foreign forces. Certainly, tribal and regional conflicts have existed for centuries and the Taliban rule starting in 1996 was a catastrophe, particularly regarding women's rights and other basic human rights.

A recent announcement by a government-funded religious council in Kabul - that women should not leave their homes unaccompanied by men - was an unwelcome reminder of the days of the Taliban. The lofty ambitions of 2001 about state-building and human rights now sound hollow; after such promises, the US and other foreign forces had a responsibility to deliver that they have failed to fulfil.

It is another indication that foreign-directed nation building, however well-intentioned, has seen its day. The US failure in Afghanistan, and to a degree in Iraq, will have long-term consequences for those countries. After a decade of war, and most recently the deaths of these 16 civilians, there is so very little to show for it.

Afghans must now rebuild. Foreigners can help those efforts, but first they must stop doing harm.