Barack Obama facing backlash over Afghanistan troop surge

President Barack Obama faced an immediate backlash over his surge plan for Afghanistan, amid fears that setting out a timetable for withdrawal could aid the Taliban and unnerve allies.

Critics said that the target date of July 2011 to begin a reduction of US forces and the transfer of security to Afghan security forces would enable the enemy to lie low and wait for the departure of US and Nato forces.

Senator John McCain, the former presidential candidate, said: "We don't want to sound an uncertain trumpet to our friends in the region."

Offering a dire warning, he said: "Hamid Karzai knows very well that if US troops leave, he'll be leaving shortly thereafter or find himself probably assassinated."

Mr Obama's political future could rest on the course he set in his speech on Tuesday night on the eight-year-old conflict, which he redefined narrowly as defeating al-Qaeda, preventing the Taliban from returning to power and creating a functioning government in Kabul.

Sir Jock Stirrup, Chief of the Defence Staff, said he was "delighted" with Mr Obama's plan.

"There's absolutely nothing wrong with having targets and milestones against which we can measure progress and against which to be frank we can force the pace," he said.

But he gave warning that a British withdrawal in earnest could not begin until 2014.

Senior aides to Mr Obama were forced to clarify the timeline, stressing that July 2011 was only a starting date and would not lead to a rapid abandonment of the Afghans.

Gen Stanley McChrystal, the Nato commander in Afghanistan, said that "the 18 month time line is not an absolute and then everyone leaves".

He added: "There are going to be more long nights, more cold mornings, more memorial services."

Robert Gates, the US defence secretary, added that more stable areas in Afghanistan's north and west would be handed over to the Afghan security forces first, and welcomed the prospect of the Taliban lying low.

"If they are inactive for 18 months it would give the United States an open run to build capacity with our allies," he said.

Anders Fogh Rasmussen, the Nato Secretary General, said he was confident that the alliance could supply a further 5-7,000 troops, while Gordon Brown called on "all our allies to unite behind President Obama's strategy".

With the prospect of renewed heavy fighting ahead, Gen Sir Graeme Lamb, a former SAS officer and now special adviser to Gen McChrystal, said the surge would allow the allies to strike the Taliban "until their eyeballs bleed".

A Taliban spokesman said: "The extra 30,000 troops that will come to Afghanistan will provoke stronger resistance and fighting."