KABUL, Afghanistan—The Taliban captured a strategic provincial capital near Kabul on Thursday, the 10th the terrorists have taken in a weeklong sweep across Afghanistan just weeks before the end of the American military mission there. Seizing Ghazni cuts off a crucial highway linking the Afghan capital with the country’s southern provinces, which similarly find themselves under assault as part of an insurgent push some 20 years after the foreign troops arrived to oust the Taliban government. While Kabul itself isn’t directly under threat, the loss of Ghazni tightens the grip of a resurgent Taliban estimated to now hold some two-thirds of the nation, and thousands of people have fled their homes. The latest U.S. military intelligence assessment suggests Kabul could come under terrorist pressure within 30 days and that, if current trends hold, the Taliban could gain full control of the country within a few months. The Afghan government may …