Ukraine’s diesel problem is often described through the language of supply diversification: more suppliers, more borders, more transport modes and more storage options should produce greater resilience. That proposition is correct only up to a point. A fuel system does not become resilient merely because several routes appear on a map, because several countries appear in customs statistics or because sufficient product exists somewhere in the wider European market. For a state operating under sustained military pressure, the relevant quantity is fuel that can be acquired, transported, transferred between networks where necessary, released from storage, quality-assured and delivered to the required destination within a useful period. The distinction matters for European defence because the same commercial railways, roads, ports, waterways, terminals, storage companies, laboratories and financial arrangements that sustain Ukraine also sit within the civil infrastructure on which European military mobility and national resilience increasingly depend. The Ukrainian case therefore provides a demanding test of what European corridor redundancy actually means.