Throughout more than 10 years of conflict in Afghanistan, Western leaders have always insisted progress was being made. Inevitably, the killing of two New Zealand soldiers, Lance Corporals Pralli Durrer and Rory Malone, and the wounding of six others in an attack by insurgents makes that more difficult to believe. This was, after all, the country's deadliest day in combat since the Vietnam War. It also occurred more than a year after New Zealand's Provincial Reconstruction Team handed control of security in Bamiyan, supposedly an area remote from the worst of the fighting, to the Afghan police. Since then, violence has intensified and it has become apparent that New Zealand troops are still an essential back-up in the struggle against insurgency.
Those soldiers are due to leave Afghanistan some time next year. The weekend's deadly attack raised the question of whether they should be pulled out earlier to avoid further losses or whether the weakness of the Afghan forces necessitates a delay to that timetable. Both courses have their proponents.
France has announced it will withdraw earlier than planned at the end of this year. It obviously thinks further progress is impossible. On the other hand, military commanders have warned Britain's Prime Minister that the path to a Taleban return to power would be cleared if too many members of the Nato force followed the French lead.
This is a time of considerable uncertainty in Afghanistan. Some encouraging pointers have been noted by General John Allen, the head of international forces there. He said earlier this year that the Taleban was in retreat, with its leadership divided. If so, this would indicate the surge of forces authorised by President Barack Obama two years ago had had an impact.
But in the long term, a stable Afghanistan will depend first on the effectiveness of the country's security forces. On the basis of the latest attack in Bamiyan province and earlier instances in Kabul when New Zealand's SAS was forced to intervene, the situation is not promising. It is apparent the army and police are beset with poor morale, corruption and a high level of desertion. British military commanders seem merely to be stating the obvious when they say it will take at least another two years, and ongoing international funding, to improve their quality and ability.
The Prime Minister has said the Provincial Reconstruction Team will still leave Bamiyan, as scheduled, in 2013. Noticeably, however, he has not ruled out sending the SAS back. It has been commended for its mentoring of Afghan forces. John Key is right to take this tack. This is not the time for cutting and running from Afghanistan. That would certainly undo much of what has been achieved. And it is important to remember that, whatever the ongoing problems, not least the corrupt Karzai Government, there have been some successes.
Take, for example, the position of Afghan women. While there have been disquieting reports that ground is being lost, there are now three million girls at school and a constitutional commitment to gender equality. It is to be hoped that even the Taleban could not orchestrate a return to the previous extreme repression. Likewise, there have been improvements in the country's economy and infrastructure. Nor should it be forgotten that the original motive for the conflict - the denial of an al-Qaeda haven - has been achieved.
This does not represent the degree of improvement hoped for when the war began. Expectations have had to be lowered as the conflict endured. But a rush to the door because of mounting fatalities would only strengthen the Taleban. It would also dishonour those who have given their lives.