After a bad few weeks for British troops in Afghanistan–15 dead already this month–the anti-war movement in the UK seems to be gathering momentum. The Stop The War Coalition, with the help of Members of Military Families Against the War, is generating substantial public support. It’s got so serious that President Obama this week felt compelled to lavish praise on the British for their “extraordinary role” in the war effort.

But Brits remain unconvinced by the western alliance’s AfPak strategy. As Simon Jenkins put it in the Guardian on Tuesday,

Obama made a serious error on coming to power. To honour his pledge to disown Iraq he felt obliged to “adopt” Afghanistan. What had begun as a punitive raid on the Taliban for harbouring Osama bin Laden morphed into a neocon campaign of regime change, counter-insurgency and nation-building. Obama rashly identified himself with this crusade and leapt from the frying pan of Iraq into the fire of the Hindu Kush.

The president now owns Afghanistan. As a result, he and his British ally, Gordon Brown, are sucked into mendacity on the scale of Iraq’s weapons of mass destruction. They talk of “clearing, holding and building” Afghan territory, to make the world safe from terrorist bases. Brown talks of fighting “to prevent terrorism coming to the streets of Britain”. His helpless defence secretary, Bob Ainsworth, tells troops they must stay until the Karzai government “can tackle the threat of the Taliban on its own”, which he knows is never.

Such explanations insult public intelligence. Terrorism does not need bases. The 9/11 attacks were planned in Germany. The safety of Britain’s streets is secured not by boys dying in poppy fields, but by sound intelligence and domestic policing. We learned last week that MI5’s former head, Eliza Manningham-Buller, specifically warned the government that British security would be harmed by intervention abroad. Ministers know this. Why do they lie?

Jenkins goes on to call on Brown “to act as he is known to believe and cut loose from the Americans in Helmand. It would take courage, but it would be the right thing to do.” There’s little chance of the prime minister following his advice. While the public grows furious about this unwinnable — and thus utterly futile — war, the debate in Westminster remains preoccupied with upping the ante. Do we need more helicopters? More troops? A civilians surge? It’s bad PR to cut and run.

Brown’s main opponents, terrified of being branded unpatriotic, offer no resistance to the war effort. The Tories want “visible progress in Afghanistan.” The best hope for the anti-war crowd should lie with Liberal Democrats on the Left. But Nick Clegg, the party’s leader, seems as dedicated as the rest of the political class to “achieving stability” in the AfPak region.

On the other hand, Canada, having suffered bad losses, has promised to pull all its troops out in 2011. If only Washington and Westminster were brave enough to admit defeat.