LONDON (AFP) - The war in Afghanistan has driven the Taliban to terror tactics but the West must make sure its own "investment in blood" succeeds in the long-term, Britain's top commander in Afghanistan said Sunday. Lieutenant General James Bucknall highlighted the need for an orderly drawdown of western troops from Afghanistan by 2015 amid fears Afghanistan could descend into chaos and extremism. "We almost owe it to those who have gone before to see the job through," Bucknall told the Guardian newspaper. "Having made this investment in blood, I am more determined," he added. "If I didn't think we could do this I would take a very different view but I am confident we can do it." Bucknall argued that the Taliban were a diminished force and doubted they would regain control of the country after the western withdrawal. "They have been driven to this much vaunted tactic of assassinations," he said in comments published on the British paper's website. "I have not seen any insurgents who have assassinated their way to power." "One hundred and forty (Afghans) have been assassinated this year...but we are taking out 130-140 mid-level Taliban leaders every month." Bucknall stressed that the Taliban were "not holding their own heartland" and that there was "absolutely no evidence anywhere in Afghanistan" that their influence was spreading. "Kabul is a flourishing capital city that is much safer than Karachi," he pointed out. Bucknall, who oversaw last year's surge of 30,000 extra US troops, urged the western coalition to work together during the two-year drawdown. "We went in together, and we go out together," he said. "Managing a coalition in a draw down requires an awful lot more work than managing a coalition during a surge." General Sir David Richards, the head of Britain's armed forces, admitted last month that the west had made tactical mistakes during the decade-long conflict. Public enthusiasm in Britain has been sapped by a steadily rising death toll among British soldiers, reports of troop and equipment shortages and U-turns in military tactics. Britain will withdraw 500 troops from Afghanistan by the end of next year, leaving 9,000 in the country. Some 390 British troops have been killed since US-led operations in Afghanistan began in October 2001. Of these, at least 345 were killed in combat. Prime Minister David Cameron has stressed that Britain's commitment to Afghanistan would endure after the last NATO combat troops leave the country at the end of 2014.