Though trucks are queued up on both sides of the river, ready to wait hours for their turn, we get through in just an hour, including the 10-minute crossing and paperwork on both sides. Our fixer is Ibou Ndiaye, a Senegalese who the American embassy hired to drive, translate, and, with his easygoing rapport with the border agents, speed transits. He shows our paperwork and gets our passports stamped. We cut to the front of the line and board as soon as the ferry arrives. On the other side, we’re met by four Mauritanians, employees of the embassy in Nouakchott, who drove six hours to meet us, help manage the north-side border guards, and get us through a series of police checkpoints on the road to the capital.

The other reason we move quickly is that the border agents don’t inspect the cargo that the courier running this trip, Brian Crawford, has piled into the Mercedes van. Regardless of the destination—whether allied or adversarial nation, conflict zone or neutral territory—the pouches skip screening at international borders (thanks to the Vienna Conventions of 1961 and 1963), and a DCS courier stays with them at all times. Crawford remains near the van, never turning away for too long. If the pouches are going by air, their courier watches them until the cargo door is locked. On ocean journeys, they prefer to keep the pouches in their cabins rather than see them disappear into the hold.

For all the fuss surrounding the things, nobody in our party knows what’s inside. The diplomatic pouch is the ultimate MacGuffin. “There’s no briefcase handcuffed to our wrists with invasion plans—it’s not like that,” Crawford jokes. They’re not always full of paper, either. A pouch might contain security equipment or, in one case, medicine that was sent to Moscow to be launched to the International Space Station. Sometimes they’re stuffed with computers, telephones, even chairs. The diplomat or office worker on the receiving end knows that whatever arrives in that orange pouch won’t have had microphones or microchips inserted along the way.

Mail moves in pouches made of durable, water-resistant orange canvas, complete with tamper-proof locks. Eric Adams

The pouches, made of durable, water-resistant orange canvas, are equipped with tamper-proof locks. Like any UPS package, each carries a label with its origin and destination and a barcode for scanning along the way. The couriers at the hubs coordinate shipments based on the size and number of pouches, the urgency of delivery, and other requests from the diplomats who make up their customers. Then they choose which shipping method makes the most sense, in terms of schedule and budget. The ASAP stuff goes by air. The furniture and photocopiers take the cheaper, slower ground and sea route.