On Newsnight on 20 August 2009, while being interviewed by Gaven Esler, US General David Petraeus said that the Afghan war is "not a war of choice". He was echoing President Obama, Gordon Brown, British military officials and others. We are told constantly that Nato forces have to be there to prevent Afghanistan from becoming a training ground for terrorist attacks on our countries. The implication is that we are killing Afghans in their tens of thousands to stop Britons at home from being killed in their tens, or, at worst, in their hundreds.

The claim that we are in Afghanistan to keep terrorists off our streets is false; our presence there increases the threat of terrorism here.

Afghanistan has not been an important planning area for any attacks on western countries and the Taliban have shown no inclination to conduct war against Nato countries outside Afghanistan (so far, but we seem to be doing our best to change their practices). Petraeus said the attacks on the World Trade Towers were planned in Afghanistan. This remark is disingenuous. Osama bin Laden may have been in Afghanistan at the time of the attacks, but had he been in New York, London, Paris or Hamburg, his whereabouts would have made no difference to the outcome. The perpetrators of the 9/11 attacks resided in Germany, Egypt, and Saudi Arabia and were trained (in part) in flying schools set up by the CIA in Florida.

Gordon Brown recently repeated the claim that 75% of the terrorist attacks planned against Britain so far have been planned in Afghanistan or Pakistan. Another dishonest statement. Mr Brown has no idea what number of terrorist attacks on Britain have been planned, nor where they have been planned, so he cannot know what percentage were planned in Afghanistan or Pakistan. The most he can even claim to know is what percentage of the terrorists attacks planned and known to our intelligence services were planned in one of those two countries.

And what about the convenient disjunction in the claims of our officials – that the terrorist plots were planned in Afghanistan or Pakistan? In which country were these alleged terrorist attacks planned? Does Brown think we don't care? If none were planned in Afghanistan, then what relevance have they to our presence there?

For the existence of any such plans to afford us grounds for killing thousands of Afghans in their own country, it would have to be shown (minimally) that such plots could not be hatched elsewhere. Clearly, that cannot be shown. So, even if such plans might have exited, or might occur in future, their existence, or possible existence, offers no grounds for our belligerent presence in Afghanistan.

Western officials talk little of the fact that when the Taliban were in power, from 1996 to 2001, opium production in Helmand was eliminated completely. Newspapers allege repeatedly that the Taliban is financing itself with sales of heroin. The media's favourite estimate of the profit made by the Taliban is $100m a year. How do they know? Second, which Taliban make this money? There is no unified command. There are at least 14 different groups being called "Taliban". Nato officials are probably the source of most claims about the drug trade in Afghanistan. Can they be trusted? Simultaneously with claims that the drug trade is run by the Taliban, we are told that it is run by Karzai's supporters. But Karzai is America's man. Can these commentators have it both ways? Or is the drug trade financing both sides?

Despite the billions of dollars that have poured into Afghanistan since 2001, no help has been given to the poor there. Actually, the condition of the poor has got much worse since 2001, which is why, contrary to yet more dishonest statements by our officials, most Afghans support the Taliban. And the plight of women (outside of the privileged families located mainly in Kabul) has also got much worse since the Taliban were overthrown (hard as this may be for us liberals to believe). The BBC's world affairs editor John Simpson was honest enough to say last week that, had the money spent so far on the Afghan war been spent on the poor, there would be no war there. At last, we see a glimmer of truth in the self-serving, meticulously disseminated "fog" of war.