Oh what a paradoxical war. Five years ago this week, the world - including all the Muslim members of the United Nations - came together to support the removal by force of the Taliban regime in Afghanistan. Today, most countries in the world have reneged on their promise to the people of Afghanistan to see that task through. Britain is one of the few nations that has made its commitment to rebuilding Afghanistan as a free country more than mere rhetoric. Yet that commitment no longer commands the support of public opinion in Britain. Tony Blair deserves some credit for stepping up the British deployment in southern Afghanistan at the beginning of this year. But that credit is more than wiped out by his failings.
The effort to rebuild Afghanistan has been fatally undermined by the disaster of the Iraq war. First, Iraq was a distraction from the sustained attention that Afghanistan required. The 5,000 British troops deployed this year should have been sent long ago - the main reason that they were not was because they were needed in Iraq. Now that they have been sent, they are too few, too unprepared, and possibly too late. The worst examples of British forces lacking the right equipment may have been rectified, but it remains the case that the military chiefs have not been given the numbers of troops required to do the job. As we report today, John Reid, when he was defence secretary, ignored the warning of his service chiefs that the numbers being sent to Afghanistan were insufficient for the task.
As a result, the strategy is wrong. Without the numbers to maintain a presence in every village, British forces are condemned to repeat the mistakes of the Americans - appearing from nowhere to seek and destroy guerrillas, then going away, leaving civilian casualties in their wake. Emails from British soldiers say they are regarded by the locals as no better than either the Taliban or the US military that went before.
Second, Iraq has contaminated the moral case for the mission in Afghanistan. Liberating the country from the Taliban dictatorship, and preventing it from providing a safe haven for al-Qa'ida, is one front in the misnamed war on terror that this newspaper supports. Yet the invasion of Iraq has increased the threat from jihadist terrorism rather than reduced it. With the al-Qa'ida camps in Afghanistan closed down, the whole of Iraq has been turned into a vast training ground for jihadism - some of which has seeped back into Afghanistan and spurred on the anti-Western forces there.
What is more, the effect of the Iraq war has been to undermine the morale of international forces in Afghanistan. The reason British public opinion now wants the troops home from Helmand is because Afghanistan is linked in the public mind - indeed was linked by the Prime Minister in his conference speech last week - with the quagmire of Iraq. In a welcome outbreak of candour last week, Jack Straw, who was foreign secretary at the time, admitted that the situation in Iraq is "dire" and appeared to blame the Bush administration for the mistakes it made after the invasion. Now that the taboo on government criticism of the US has been lifted, it is vital that British forces in Afghanistan are not condemned to repeat - and pay for - American mistakes there, too.
Iraq casts its shadow over Afghanistan in another way, as well. Because the justification for our soldiers' presence in Iraq is so flawed, public opinion in the UK, as in most countries, is highly sensitive to casualties - not just in Iraq but elsewhere. Mr Reid complains that he was misreported as suggesting in April that the British deployment would be casualty-free. What he said was: "If we came for three years here to accomplish our mission and had not fired a shot at the end of it, we would be very happy indeed." It was an uncontroversial sentiment, as he contrasted the British mission of reconstruction with the American one of counter-terrorism. But it left an unfortunate impression.
This country's mission in Afghanistan requires a fresh start. The case for fulfilling our promise - and that of the wider international community - to the Afghan people is overwhelming, in terms of simple morality as well as self-interest. Having decided five years ago that the Mullah Omar regime could not stand, it would be intolerable to allow the Taliban to regroup and regain control of parts of the country. But Mr Blair has long since lost the moral authority to make that case. It was notable that Gordon Brown, in his speech in Manchester last week, said: "We will take any necessary steps and find all necessary resources to ensure, whether in Iraq, Afghanistan or anywhere else, that there is no safe haven for terrorists." He must be held to that.
The truth is that the international forces are not winning the war in Afghanistan at the moment. But, as Sandy Gall argues on the facing page: "Unlike Iraq, the Afghan war is winnable, although it will be tough." It requires what the Army brass calls a "drawdown" of troops in Iraq so that they can be redeployed in a war that can - and must - be won. It requires a change of strategy, away from the hit-and-run methods of the forces of the United States, the distracted superpower. Our brave armed forces deserve nothing less.