Taliban fighters have seized their former stronghold of Kandahar and now control all but a few major cities as U.S. forces prepare to finally end a 20-year occupation of Afghanistan. After several weeks of siege, Taliban forces overran the southern city on Thursday. It’s the 12th provincial capital seized by the Islamist group in about a week and the most significant, as both a major trading hub and birthplace of the Taliban movement in the 1990s. The ferocity of the Taliban advance has led to fears that the capital, Kabul, where tens of thousands of civilians have fled, could fall within weeks. Both the United States and Britain have sent in extra forces to help support an evacuation of their nationals, although President Joe Biden insists the Afghans have to be left to fight for themselves.