U.S. President Donald Trump repeatedly urged Ukrainian President Volodymyr Zelensky to stop strikes on Russian oil refineries during a phone call, Axios reports, citing a source familiar with the conversation. “The word ‘diesel’ came up many times during the call,” the outlet quoted the source as saying.

This was not Trump’s first appeal. On September 13, speaking to reporters on the sidelines of the Amgen Irish Open in Ireland, he publicly said:

“Mr. Zelensky needs to do one thing: he must stop taking out diesel production in Russia. Let him attack targets, but not diesel fuel, because that creates shortages.”

According to the U.S. president, the situation is not related to the Middle East. He argues that strikes on Russian facilities are driving the global increase in diesel prices. The Ukrainian president, by contrast, believes that higher diesel prices are being caused less by refinery strikes than by the disruption of traffic through the Strait of Hormuz following the U.S.-Iran conflict.

The statements came amid an escalation of attacks on Russia’s refining sector. On the night of September 20, the Moscow Refinery, which supplies around 40% of the capital’s fuel market, was attacked by drones. Both of its primary crude processing units — AVT-6, accounting for 53% of capacity, and Euro+, accounting for 47% — were damaged by fire. From September 21, the refinery’s fuel was no longer offered for trading on the St. Petersburg Commodity Exchange.

On the night of September 22, according to Reuters reports, two major refineries were hit: Bashneft-UNPZ in Ufa, with a capacity of around 7.5 million tonnes per year, and Rosneft’s Kuibyshev Refinery in Samara, with a capacity of around 7 million tonnes per year. The facilities were reportedly struck again on the night of September 23. A storage tank damaged the previous day was burning at the Kuibyshev Refinery, while smoke was seen rising near the industrial site in Ufa.

Thus, five major Russian refineries were affected by drone attacks during September: the Ryazan Refinery on September 6, the Saratov Refinery on September 11, the Syzran Refinery on September 15, the Yaroslavl Slavneft-YANOS Refinery on September 17, and the Moscow Refinery on September 20. The average diesel price in the United States reached USD 6.50 per gallon for the first time. Analysts note that both the Middle East conflict and strikes on Russian refineries are putting pressure on the global refining system.