Europe has approximately six weeks of jet fuel remaining, International Energy Agency Executive Director Fatih Birol warned Thursday, saying flight cancellations could follow “soon” if the Iran war continues to block oil shipments through the Strait of Hormuz.

“In Europe, we have maybe six weeks or so (of) jet fuel left,” Birol told the Associated Press from his Paris office. “If we are not able to open the Strait of Hormuz … I can tell you soon we will hear the news that some of the flights from city A to city B might be canceled as a result of lack of jet fuel.”

The warning marks a new threshold in what Birol called “the largest energy crisis we have ever faced,” with more than 110 oil-laden tankers and over 15 liquefied natural gas carriers stranded in the Persian Gulf and unable to reach world markets. Nearly 20% of the world’s traded oil passes through the Strait of Hormuz in peacetime.

Airlines cut flights, monitor fuel stocks

Dutch carrier KLM said it is cutting 160 flights to and from Amsterdam’s Schiphol airport in May — about 1% of its total European routes — citing “rising kerosene costs.” The airline said a limited number of flights were “no longer financially viable to operate.”

KLM and U.K.-based budget carrier easyJet both said Thursday they were not experiencing current fuel shortages, without elaborating on the IEA warning. U.S. carrier Delta Air Lines said it was aware of Europe’s “potential jet fuel supply issue” and monitoring the situation, though it did not expect immediate impacts. All three carriers have already absorbed higher costs from the disruption.

Beyond cancellations, some carriers are also raising ticket fares and add-on fees in response to elevated fuel costs, Birol said.

Recession risk if strait stays closed

Birol said the economic consequences of a prolonged closure would extend well beyond aviation. “Many government leaders tell me that if Hormuz is not open until (the) end of May, many countries — starting from the weaker economies — are going to face huge challenges,” he said, warning of outcomes ranging from high inflation to recession.

He described the pain as unevenly distributed. “The countries who will suffer the most will not be those whose voice are heard a lot. It will be mainly the developing countries. Poorer countries in Asia, in Africa and in Latin America,” said Birol, a Turkish economist who has led the IEA since 2015.

“Some countries may be richer than the others. Some countries may have more energy than the others, but no country, no country is immune to this crisis,” he added.

Toll system draws IEA objection

Birol also objected to a “toll booth” arrangement that Iran has applied to some ships, allowing passage through the strait for a fee. He cautioned that allowing the system to persist could set a precedent for other critical global shipping lanes, including the Malacca Strait in Asia.

“If we change it once, it may be difficult to get it back,” he said. “I would like to see that the oil flows unconditionally from the point A to point B.”

Infrastructure damage slows recovery

Even if a peace deal were struck, the recovery would take time. Birol said more than 80 key energy assets in the region have been damaged, with more than one-third severely or very severely damaged.

“It will be extremely optimistic to believe that it will be very quick,” he said, projecting that restoring pre-conflict production levels could take up to two years.

The IEA, which advises governments on energy policy and coordinated a record release of emergency oil reserves earlier in the crisis, has warned for years about the strategic importance of the Strait of Hormuz, Birol said.

“Energy and geopolitics have been always interwoven,” he said. “But I have never, ever seen … such a dark and long shadow of geopolitics.”