A report that senior generals are pressing the Government to withdraw British troops from Iraq in order to beef up our commitment in Afghanistan underlines how desperately we need more soldiers there. But with the Americans against any British withdrawal from Iraq, and most European allies too chicken to fight in the south, we are piggy in the middle.

Hence the dire forecasts of failure now so commonplace. Worryingly, they are based not so much on pub punditry as on the flow of angry emails from officers in the thick of fighting in Helmand Province and other parts of the south. RAF close air support had been "utterly, utterly useless", according to Major Jamie Loden of 3 Para in a leaked email about the battle for opium town Sangin. A female Harrier pilot "couldn't identify the target", he wrote, fired two phosphorus rockets that just missed the British compound and then strafed their perimeter, "missing the enemy by 200 metres". Another British officer who criticised the RAF's performance said the American A10 pilots had been, by comparison, first-class.

This is ironic, since the American Air Force has been much criticised for repeated incidents of "friendly fire". In one notorious case, elders driving to Kabul for President Karzai's inauguration were mistaken for a Taliban convoy and shot to pieces. Dozens were killed or wounded. Most of these incidents have occurred in the Pushtun south and east, the Taliban heartland, and have done enormous damage to Karzai who, although a Pushtun, is often accused of being an American stooge.

And yet he has won two elections for the presidency with no challenger in sight and, until about a year ago, the country seemed on the road to relative peace and prosperity. So what has gone wrong? In a word, Iraq. Having bombed the Taliban out of power in 2001, less than two years later the Americans were diverting men, money and attention to Iraq. The switch has proved costly. Reconstruction, which was just beginning, stalled. There seemed to be no money or will to keep the wheels turning.

A government adviser from the province of Paktika told me no one was stopping Taliban infiltration from Pakistan because border guards were not being paid. "They leave their barracks in the morning to go and do a job somewhere else... It's the only way they can feed their families... A few thousand dollars would solve the problem."

This situation is mirrored all over the south. In Helmand, Afghanistan's biggest province and its biggest opium producer, there was practically no support for the government or police when the British arrived. US troops concentrated solely on the hunt for Osama bin Laden. The field was left wide open to an alliance of Taliban and drug-runners. The drug gangs gave the Taliban cash in return for protection. This was the hornets' nest into which 3 Para and the rest of the British spearhead were dropped last summer.

And yet, despite the odds, the corner may well have been turned. In a series of recent battles, the British and Canadians have inflicted heavy casualties on the Taliban. Most Afghans do not want the Taliban back in power. They reject their vision of society as a dead end. But they are swing voters. They need to be convinced the Afghan government, Nato and the international community can deliver jobs, a living wage, and security.

Unlike Iraq, the Afghan war is winnable, although it will be tough. But as soon as Lt-Gen David Richards, Britain's overall Nato commander, gains control of the battlefield and generates security across the country, which he is confident he can do, reconstruction and development must take off.

Sandy Gall, formerly of ITN, is chairman of Sandy Gall's Afghanistan Appeal, which treats disabled Afghans