Restoring an airfield after damage is not a single engineering act. A repair material can have suitable properties without ever having been assessed for the pavement application in question. A repair system can be installed correctly without having been tried with the aircraft that will use it. An engineering team can complete a training scenario without showing that the same people and equipment are held ready for operations. A surface can be physically intact without the evidence that the responsible authority needs before it permits aircraft to use it under defined conditions. The operational problem is therefore not only how quickly damaged pavement can be filled or covered. It is how materials, equipment, skilled labour, inspection and technical responsibility combine to make a particular repaired surface usable for a defined aviation purpose. For European rearmament the question is sharper still: which of those elements Europe can already supply, test and oversee itself, which it obtains through allies, and what the public record allows anyone to say about the difference.