Robert Fisk: Watch us lead the UN donkey up the Khyber

What happens to Afghan women and children when Western troops leave? (Getty Images)

So back to THAT BLOODY WAR. I mean not the Syrian one – where we're going to stay hands off – or the Libyan one (where we were hands on, but not touching the ground). Nor the Iraqi one, which is a war at 60-a-day fatalities (pretty much equal with Syria's daily death toll, though we can't make that comparison). Nope. Of course, I mean the Afghan war which we fought in 1842 and in 1878-80 and in 1919 and from 2001 to 2014 (or 2015 or 2016, who knows?). We wouldn't let them down this time, we said about the Afghans – or Lord Blair of Kut al-Amara said – in 2001. Oh yes we will.

We learned our lesson in Iraq where our belief in a bloodless victory – bloodless for us, very bloody indeed for them – came hopelessly unstuck. We died, too. Which is why the Americans went home. Vietnam was supposed to see the end of Western casualties. But we are not immune to death. No more in Afghanistan than in Iraq. So we are going home there, too. We may not leave behind a "perfect" democracy – the Americans were admitting years ago that we might not leave a "Jeffersonian democracy" behind. Ho-hum, no we're not!

And we must quietly abandon all the stuff about our being in Afghanistan to fight terror – on the grounds that if we don't fight it there, it will be heading for Kent on the Channel Tunnel – because it's a load of old cobblers. The 7/7 bombings had more to with our being there than our not being there.

The French have a unit in Afghanistan, but it did not prevent the unspeakably cruel murders in France last week. I'm becoming, I must say, a bit amazed at old Obama. He's been carrying on up the Khyber for so long that I suspect he has forgotten his own words of wisdom.

I admit to a dark chuckle when the US President announced a few days ago that Syria could not hold a free and fair election while it was at war. Obama was absolutely right. But we therefore have to forget that the same Obama accepted the results of two corrupt elections in an Afghanistan at war – ballot boxes stuffed in traditional ways – and then telephoned Kabul to congratulate President Karzai on his fraudulent victory. Doesn't anyone check the screenplay in Washington these days?

I have to say that when I read the other day what Franklin D Roosevelt had to endure during the 1944 US elections – when Thomas Dewey's running mate, Governor John Bricker of Ohio, said that Roosevelt's New Deal had "adopted the basic doctrines of Nazism and Fascism" – I came to the conclusion that Obama was having a pretty easy time of it. Being called a leftie is tame stuff compared with that. But Americans want their soldiers home (which is what Obama promised them) and home they will come.

Some 300,000 Afghan troops are going to take over from us – yet Lieutenant General Curtis Scaparrotti, the second most senior officer in Afghanistan, has said that only 1 per cent of Afghan battalions can fight independently. That's not exactly the Grenadier Guards.

Michael Glackin has written most eloquently that the whole Afghan operation's remit has been so redefined that it is completely meaningless. He points out that Blair originally told us that stamping out the Afghan trade in heroin was a key element in the "war on terror". Before we went there in 2001, heroin production stood at 185 tons. Now it stands at a whacking 5,800 tons, according to the UN. Afghanistan's drug trade now provides 15 per cent of the country's GDP. Thank God for Lord Blair of Kut al-Amara.

And we want to chat to the Taliban in Qatar – having got our measure they've just said goodbye to that – as if we are promising them a deal. Kill more of our soldiers – Glackin again – and we'll leave in 2014! Shoot at the British Expeditionary Force and we'll head for Dunkirk.

Of course, I hate Second World War comparisons of the Saddam-is-Hitler, the Taliban-are-Nazis variety. But I've said before that somewhere along the way, we lost our ability to take casualties; we abandoned – rightly so, in my view – the huge capacity for suffering and grief that we were expected to tolerate in two world wars in the last century. Compare our casualties in Afghanistan to the 20,000 British dead on the first day of the Somme and we've obviously said, when it comes to war dead, enough is enough. Same in Korea. And Vietnam, of course.

But if we are right to do that, can we any longer go around, bombing Libyans and threatening Iranians and sort of threatening Syrians? I guess we really do have to bring on the UN donkey more often, along with his heavy bags of failure and past uselessness. And I bet, come 2014, we shall see this sad beast clip-clopping up the Khyber while we clap and pat ourselves on the back for our sacrifice.

Which reminds me. What happens to the Afghans? The women? The schools? The bridges? And all that corruption which has corroded around our failed mission? They know we are leaving.

The Taliban know we are leaving. The Americans and British know we are leaving. Obama and Cameron have to pretend that we're not, or that we are, but only if we really, really think we've won.