<p><br /> David Cameron has said British troops could start withdrawing from Afghanistan as early as next year.<br /> </p><p><br /> The Prime Minister, visiting the country on an unannounced trip, said: "In terms of next year, I think that it is possible. We have to deliver on the ground what's necessary. What I have seen today gives me cause of cautious optimism."<br /> </p><p><br /> Mr Cameron also said the death of a paratrooper in an apparent friendly-fire incident in southern Afghanistan was "very tragic" but a consequence of "the fog of war".<br /> </p><p><br /> "It is absolutely tragic when incidents like this happen and my heart goes out to the family concerned, to lose a loved one and to lose a loved on in this way is obviously a terrible thing. There will have to be a proper investigation," Cameron said.<br /> </p><p><br /> Mr Cameron, who arrived on Monday, shrugged off US and Afghan criticism of the troops' performance, saying it no longer held true.<br /> </p><p><br /> Troops deployed in the Taliban stronghold of Helmand were "not up" to the task of securing the province, American diplomats said in cables released by WikiLeaks last week.<br /> </p>
