Nato’s next commander in Afghanistan warned yesterday that the West could lose the war against the Taleban if it fails to gain the support of the Afghan people.

In a blunt assessment of the mission, US Army Lieutenant-General Stanley McChrystal predicted increasing casualties as President Obama’s surge of troops progresses over the summer.

Civilian deaths in Afghanistan, especially from US airstrikes launched from unmanned drones, have already inflamed anti-American sentiment in parts of the country.

“How we conduct operations is vital to success. This is a critical point. It may be the critical point. This is a struggle for the support of the Afghan people,” General McChrystal told the Senate Armed Forces Committee during his confirmation hearing.

“Our willingness to operate in ways that minimise casualties or damage — even when doing so makes our task more difficult — is essential to our credibility.”

Last month Mr Obama dismissed his previous Afghan commander, General David McKiernan. Robert Gates, the US Defence Secretary, said that it was time for “fresh thinking” in a war that officials say the US is not winning.

General McChrystal, whose background is in the secretive world of special operations, said that he wanted to bring a “classic counter-insurgency strategy” to the war. “I believe it is winnable but I don’t think it will be easily winnable,” he said. “Success will not be quick or easy. Casualties will likely increase.”

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