The US Defence Secretary Robert Gates says he is convinced that the US strategy in Afghanistan is working. After visiting US bases in Afghanistan over two days, Mr Gates said the goal of pulling American troops out of major combat roles by 2014 can be met. He admitted that NATO and Afghan forces were suffering more casualties but added that the security situation has improved. The US President Barack Obama has set July 2011 as the date to begin withdrawing forces from Afghanistan. But the commander of NATO forces in Afghanistan, General David Petraeus, has said that he may advise President Obama to delay the exit plan.