“We do not negotiate with terrorists, we put them out of business”, was the White House response to a new Bin Laden tape offering a truce.

There can’t be many people who believe that statement. Certainly not the second part. Not four and a half years after the invasion of Afghanistan.

Trumpeted as everything from “pre-emptive self-defence” to “humanitarian interventionism”, the mission has transparently failed.

Not only does Bin Laden speak to the world, but so does his deputy Ayman al-Zawahri whose latest video, released shortly after the Pakistani village of Damadola was pulverised amid claims of his demise, took the shine off Bush’s State of the Union address.

Failure is also marked by an economy which is now variously estimated as 30 per cent to 60 per cent based on opium, coming from zero in 2001.

Britain, given specific responsibility for eradicating this, has overseen its spread to 28 out of 32 provinces. Despite a small dip last year, 2006 is predicted to be a bumper crop exceeding 1999’s record production. It is now the source of 90 per cent of the global heroin market.

Hamid Karzai’s government is a puppet regime, with a writ running little further than the outskirts of Kabul and wholly dependent on billions of dollars of western aid. Last year’s parliamentary elections saw a low turnout of 53 per cent, with warlords and ex-Taliban commanders winning over half the seats.

What passes for government is based on a crude alliance of these elements with the drug barons. Only recently Karzai had to sack his appointee to the governorship of Helmand, the province where British troops are to be based, for his links with the drugs trade.

The government’s vulnerability is symbolised by the inability of the country’s Muslim clergy – the only institutional infrastructure outside of the centre – to reach a consensus on its legitimacy.

In the fifth year of the military takeover of Afghanistan by the world’s richest and most powerful nations, it still ranks among the half dozen poorest in the world, with a malnutrition level of 70 per cent, the highest globally.

This is the context for the recent announcement of an expansion of British military involvement – from 850 to 5,700 – at a cost of over £1 billion.

It seems a long time ago now, but the original invasion – though subject to mass opposition – was not met by the scale of popular revolt triggered by the Iraq war.

People were outraged by 9/11, they still trusted Blair, and many believed the invasion was motivated by humanitarianism. Even women’s rights were high on a brisk agenda that promised a new start for a country blighted by two decades of war, super-power games and fanaticism.

Little comfort to Ali Mohaqiq Nasab, editor of Haqooq-i-Zan (Women’s Rights) magazine, sentenced in October to two years for “blasphemy” after criticising stoning and lashing for “crimes” such as adultery.

Controversy rages up to the highest level of the military and political establishments over the aims and viability of this new deployment. Is it “nation building” or “anti-terror”?

Defence Secretary John Reid was clearly hedging his bets when he said, “We do not go there with the primary purpose of waging war”. That’s a license to do pretty much anything.

New York University analyst Barnett Rubin has commented that, “You can’t have a nation-building policy on the one hand and a policy to kill off a major sector of the economy on the other”. And Foreign Secretary Jack Straw has conceded that the drug problem, “is more deep-seated than anybody understood when we began this”. Not understood, perhaps because it was non-existent.

Then there’s the question of detainees. Will they be handed to the US and end up in Guantanamo or “rendered” to secret camps elsewhere to be tortured and executed?

When asked recently by the House of Commons Defence Committee, Martin Howard, Ministry of Defence director general responsible for operation policy, could not say.

“I find that a bit odd” responded the chair James Arbuthnot MP, putting it mildly.

This is the third phase of imperialist military intervention in Afghanistan since 1980. First Muslim guerrillas were trained and funded to fight the Soviet-backed government, then the country was invaded to smash the Taliban regime that grew out of that resistance movement.

Now the fight is both against regional warlords and drug barons who were allies in phase two and a resurgent Taliban who (it seems) weren’t defeated after all.

Behind a need to give the USA cover, overstretched in an increasingly unpopular war in Iraq, lies a wider regional power play.

Iran played a significant role in the invasion and retains influence in the North West and in the Kabul government.

This and growing influence in Iraq is perceived as part of a so-called “Shia crescent” stretching from Lebanon, through Syria to Afghanistan. Alongside sabre rattling over Tehran’s nuclear ambitions, Nato strength in Afghanistan aims to box the country in and destabilise it.

Iranian foreign minister Manoucheher Mottaki has commented that the US, even with 200,000 troops on the ground in Iraq and Afghanistan, is unable to impose its will on the region.

Bush and Blair are desperate to show otherwise.

Unfortunately for them potential partners like France, Germany and Spain won’t join in. And popular opposition almost derailed Dutch troop deployment.

The anti-war movement needs to get Afghanistan back in its sights as the squaddies fly in over the coming months.