In 2006, the US forces turned over security of the country to NATO-deployed forces in the region, integrating 12,000 of their 20,000 soldiers with NATO's 20,000. The remainder of the US forces continued to search for Al-Qaeda militants. The Canadian military assumed leadership and almost immediately began an offensive against areas where the Taliban guerrillas had encroached. At the cost of a few dozen of their own soldiers, the British, American, and Canadian Forces managed to kill over 1,000 alleged Taliban insurgents and sent thousands more into retreat. Many of the surviving insurgents, however, began to regroup and soon after began to engage both NATO and Afghan National Army forces, starting a protracted war that lasted till 2021, with the withdrawal of Western forces and the Taliban victory.