US and Afghanistan closing in on security deal The agreement would also allow US soldiers to raid homes under exceptional circumstances during fighting against al-Qaeda and the Taliban. Afghans have long objected to the raids which have often ended with civilians being killed. Aimal Faizi, a spokesman for Mr Karzai, said the Afghan president had relented on the issues of raids and immunity in return for a letter from Mr Obama offering assurances that the powers would "not be misused." The whole idea of having a letter was to acknowledge the suffering of the Afghan people and the mistakes of the past. That was the only thing that satisfied [Mr Karzai]," said Mr Faizi. The White House remained tight-lipped on the details of the agreement and stressed that nothing was finalised until the deal received the approval of the loya jirga, which begins meeting Thursday. "This negotiation or this agreement is not reached until the loya jirga has passed judgment on it," said Jay Carney, the White House press secretary. The US State Department said there were still "some final issues that we are working through" but did not deny that a deal appeared close at hand. The breakthrough appears to have come following discussions between Mr Karzai and John Kerry, the US secretary of state, on Tuesday. According to the Afghan government Mr Kerry originally offered to write the letter but the Afghans said they would only accept it if it came from Mr Obama himself. The letter and the text of the agreement are expected to be presented to the 2,500 members of the tribal council. Although the loya jirga's decision is not technically binding, Mr Karzai has said he would not move ahead without its support. It was not clear exactly how many Nato troops would remain in Afghanistan after the international force's combat mission comes to an end next year. An early draft of the agreement obtained by NBC News did not name a specific figure but Afghan officials said it could be as high as 15,000 while US said the number was likely to be closer to 7,000. There are currently 86,000 Nato soldiers in Afghanistan, including 60,000 Americans and 7,900 British troops. A smaller number of British troops may also remain in Afghanistan if the agreement is finalised. The international troops would continue to train Afghanistan's security forces and maintain military outposts from which to combat al-Qaeda.