Richard Armitage, a former US deputy secretary of state, has told Al Jazeera that the conflict in Afghanistan may be "spinning out of control".
"The situation in Afghanistan may be spinning out of control more quickly than we are gaining control and it's of course exacerbated by their next-door neighbour Pakistan," Armitage, who served in the administration of George Bush, the former US president, said on Tuesday.
He also said Barack Obama, Bush's successor, got it "a little backwards" sending thousands of extra troops to Afghanistan before his administration completed a review of US policy on the region.
"I was a little taken aback by the fact that we surged 17,000 soldiers to Afghanistan before we completed the review - that seemed to be a little backwards," he said.
Obama said in February he was deploying an extra 17,000 troops to Afghanistan to take on a resurgent Taliban.
As part of the review on US policy on Afghanistan and Pakistan unveiled in March, he also said he was sending 4,000 US troops to train Afghan security forces.
Obama's strategy also included proposals to counter persistent attacks by Taliban and al-Qaeda fighters across the border with Pakistan and additional development aid for both nations.
The Pakistani government has also made a number of deals with fighters there in an attempt to head-off their growing strength.
The US currently has about 38,000 troops in Afghanistan in addition to around 42,000 Nato troops.
The Taliban-led campaign has steadily gained strength in recent years, with 2008 the deadliest year so far.
Armitage left the Bush administration after he was re-elected president in November 2004.
He announced his resignation the day after his superior, Colin Powell, Bush's secretary of state, quit.