KABUL, Afghanistan—A panicked crush of people trying to enter Kabul’s international airport killed seven Afghan civilians in the crowds, the British military said Sunday, showing the danger still posed to those trying to flee the Taliban’s takeover of the country. The deaths come as a new, perceived threat from the ISIS affiliate in Afghanistan has seen U.S. military planes do rapid, diving combat landings at the airport surrounded by Taliban terrorists. Other aircraft have shot off flares on takeoff, an effort to confuse possible heat-seeking missiles targeting the planes. The changes come as the U.S. Embassy issued a new security warning Saturday telling citizens not to travel to the Kabul airport without individual instruction from a U.S. government representative. Officials declined to provide more specifics about the ISIS threat but described it as significant. They said there have been no confirmed attacks as yet by the terrorists, who have battled …