In January 2006, NATO's focus in southern Afghanistan was to form Provincial Reconstruction Teams with the British leading in Helmand Province and the Netherlands, Australia and Canada leading similar deployments in Orūzgān Province and Kandahar Province respectively. The United States, with 2,200 troops, stayed in control of Zabul Province. Local Taliban figures voiced opposition to the incoming force and pledged to resist it. NATO expands in southern Afghanistan From January 2006, a NATO International Security Assistance Force (ISAF) force started to replace U.S. troops in southern Afghanistan as part of Operation Enduring Freedom. The British 16th Air Assault Brigade (later reinforced by Royal Marines) formed the core of the force in Southern Afghanistan, along with troops and helicopters from Australia, Canada and the Netherlands. The initial force consisted of roughly 3,300 British, 2,500 Canadians, 1,963 from the Netherlands, 280 from Denmark, 240 from Australia, and 150 from Estonia. Air support was provided by US, British, Dutch, Norwegian and French combat aircraft and helicopters. In 2006, southern Afghanistan has faced the deadliest spate in violence in the country since the ousting of the Taliban regime by U.S.-led forces in 2001, as the newly deployed NATO troops battled resurgent militants. Operation Mountain Thrust was launched on May 17, 2006 with the purpose of rooting out Taliban forces. Canadians were one of the leading combatants and the first fighting took place during the Battle of Panjwaii. Complex mud-walled compounds meant that the fighting in the rural Panjwaii district was similar to urban fighting in some places. Daily firefights, artillery bombardments, and coalition airstrikes turned the tide of the battle in favour of the Canadians. On July 3, 2006, it was reported that British Army leaders had warned Prime Minister Tony Blair that victory was not certain in Afghanistan, and were calling for more reinforcements. More than 1,100 Taliban fighters were killed and almost 400 captured in the month-and-a-half-long operation. In July 2006, command of the international forces in southern Afghanistan was passed to NATO forces under British General David J. Richards. Regional command in the south was led by Canadian General David Fraser. In November 2006, Dutch Major-General Ton van Loon took over NATO Regional Command South in Afghanistan for a six-month period from the Canadians. Canadian Forces, which came under NATO command at the end of July, launched Operation Medusa in an attempt to clear the areas of Taliban fighters once and