‘THE BREATH OF THE PERSON IS UPON YOU’: The tight security at the Kabul airport is designed to keep the people and the planes inside safe, but like all airports, it has an unavoidable weak link — the checkpoint where people are screened for weapons or explosives.

It was at that critical nexus where U.S. troops were performing a mission fraught with danger, patting down and searching Afghan civilians desperate to escape to new life before allowing them into the sanctuary of the airport compound. More than 100,000 people had been cleared for departure, but on Thursday, Marines at the Abbey Gate were performing their mission with the knowledge that U.S. intelligence reports were warning of an imminent attack.