Mr Obama used a 60 Minutes interview on Sunday night to set out more limited objectives in Afghanistan, where he said the “central mission” was to prevent terrorists plotting violence against America. “There’s got to be an exit strategy,” he said. “There’s got to be a sense that this is not perpetual drift.” Mr Obama expects a better return for the investment of so much blood and money in Afghanistan than a weak Government riddled with corruption that spends much of its time complaining about the American-led Nato forces.

Obama has approved an additional 17,000 U.S. troops to go to Afghanistan this year, bolstering 33,000 already there, to counter the Taliban’s growing resurgence in recent years in the volatile southern part of the country. He has described that as the most difficult decision of his young presidency.

In the coming days, he is expected to announce his broader rethinking of U.S. strategy and goals in the war, including changed tactics and lowered expectations for the difficult conflict. Top aides to Obama are recommending that the United States combine a boost in military deployments with a steep increase in civilian experts to combat a growing insurgency in Afghanistan, senior U.S. officials say.