That letter may well be in the back of Mr Obama's mind as he agonises over how to stabilise the situation in Afghanistan and secure a dignified exit for the US-led Nato forces struggling to cope with the Taliban insurgency. 此信或许暗合奥巴马潜意识中的顾虑。他正在烦恼如何稳定阿富汗局势,让疲于应对塔利班叛乱组织的、以美国为首的北约军队体面地撤兵。