Sources close to the administration said the policy, which is the only direct means the US has of targeting terrorist leaders, was being “re-evaluated” because of its adverse affect on public opinion and its value to the Taliban as a propaganda tool.

“I have no doubt there is a change of mood,” said a Washington source. “The administration recognises that the political challenges are so immense for Pakistan’s government that the US has to re-evaluate what it has regarded as an otherwise successful programme.”