Same thing when we used to fly into different countries and fuel up the plane, we signed a receipt if it was a military base and they billed the US and eventually it came out of our own operating budget for the squadron.
When fueling at a civilian airport overseas we had a Cadillac chit we could use, we would pay for fuel, landing fees (if charged), and ramp services with it. We would fill it out, give it to the head honcho and they would present it to the embassy for reimbursement.
bob