The other issue, says Justin Bronk of the Royal United Services Institute, a think-tank in London, is the state of Ukraine’s airfields. Soviet runways were built like floor tiling: panels of concrete blocks with sealant in between. That allows them to withstand the expansion and contraction from extreme heat and cold. It also means that moss, stones and other debris accumulates in between. The Gripen, with smaller air intakes that sit higher up on the fuselage, would cope with this far better than the F-16, says Mr Bronk.