Soon thereafter the US and its allies invaded Afghanistan, and together with the Afghan Northern Alliance removed the Taliban government as part of the war in Afghanistan. As a result of the US special forces and air support for the Northern Alliance ground forces, a number of Taliban and al-Qaeda training camps were destroyed, and much of the operating structure of al-Qaeda is believed to have been disrupted. After being driven from their key positions in the Tora Bora area of Afghanistan, many al-Qaeda fighters tried to regroup in the rugged Gardez region of the nation.