Earlier this year, European aviation officials sounded the alarm.

With the conflict in the Persian Gulf halting the region’s jet fuel exports to Europe, airport officials warned of a systemic shortage. Lufthansa slashed 20,000 flights. Jet fuel prices doubled.

The shortage, however, was averted – at least for now. U.S. suppliers ramped exports to a record 442,000 barrels per day, more than double the five-year norm, and Nigeria’s Dangote refinery also provided more fuel to the region.

Europe found supply. But finding supply and affording supply are two different things.

As one European fuel analyst told CNBC:

“While we can import more, and we are, from the U.S. and Nigeria, we have to fight for every cargo that’s going to come. We have to fight against Singapore, against Australia – and the price … just goes higher and higher.”

That’s the reality of import dependence in a disrupted fuel market. While higher oil prices have raised fuel costs worldwide, regions with adequate refining capacity can produce their own supplies rather than compete for scarce imports – sparing consumers from paying an additional premium.

California’s recent embrace of fuel imports shows this phenomenon in action.

According to S&P Global, since the closure of the Phillips 66 Wilmington and Valero Benicia refineries, Los Angeles jet fuel has swung from trading at 80 cents below global benchmark prices to 52 cents above the benchmark – an increase of $1.32 per gallon.

California gasoline and diesel prices have followed the same pattern, with premiums over global benchmarks growing substantially over the past year.

The implication is clear: when California had more refining capacity, local production kept prices competitive. As that capacity has shrunk, the state has increasingly paid a premium to source supplies from global markets.

California Energy Commission Vice Chair Siva Gunda has acknowledged this reality, recently telling an Assembly committee hearing:

“The important piece to note there is as the gallons become tighter across the globe, we have to compete, and … that kind of pricing will be baked into the price at which we acquired those imports and hence passed to the consumers.”

Europe has avoided war-related fuel shortages. California may too. But both regions are discovering a harsh reality: import dependence means someone else decides what you pay for the fuels you need.