U.S. President Donald Trump blamed Ukrainian attacks on Russian refineries for a drop in global diesel exports and soaring prices around the world, saying President Volodymyr Zelensky "wanted to cause trouble in the world."
"He damn well better stop," Trump said, before suggesting Ukraine should "get a different leader who can make a deal."
But others blame the U.S.-Israeli war against Iran, which has slashed exports of refined fuels from the Persian Gulf region.
After Trump announced a controversial deal to import diesel from Russia, promising "lower prices for Americans", BBC Verify examines the factors affecting diesel supplies in recent months and in recent years.
Data shows that while the conflicts in Ukraine and Iran have both sharply reduced global diesel exports, the decline in supply from Gulf countries due to the war with Iran has been even greater.
What happened to global diesel prices?
While rising diesel costs are a direct hit to motorists, there are wider concerns as diesel is widely used in trucks, vans and ships that form the backbone of global supply chains. Any increase in transportation costs is likely to be passed on to consumers in the form of higher prices.
According to the latest data from the US Energy Information Administration, the average retail price of diesel in the United States was US$6.20 per gallon on October 5 (US$1.64 per liter; RMB 10.97; NT$52.4), slightly lower than the record high of US$6.50 per gallon set on September 21.
Before the war with Iran broke out, diesel fuel cost about $3.50 a gallon in the United States.
Likewise, average UK diesel prices are currently close to record highs. Figures from the Department for Energy Security and Net Zero show that the price per liter of diesel on October 5 was 199 pence (£1.99; US$2.63; 17.6 yuan; NT$84.04).
In 2025, some 6.8 million barrels per day of diesel will be exported to global markets, according to shipping data firm Kpler. Exports account for about a quarter of total global diesel consumption, with the remainder coming from domestic production in each country.
By September 2026, global diesel exports have dropped to 5.8 million barrels per day, a decrease of about 1 million barrels.
Some countries, notably the United States, have increased diesel exports over the past year, but overall global net exports have remained in decline.
Analysts say it is this drop that has pushed up the retail price of diesel.
How much supply has Russia lost?
In 2025, Russia exported approximately 810,000 barrels of diesel per day, but this had dropped to approximately 140,000 barrels by September 2026, a decrease of approximately 670,000 barrels per day.
One of the reasons for the decline in Russian exports is Ukraine's continued attacks on the country's oil refineries. These refineries process crude oil into diesel fuel.
How much supply has been lost from the Middle East?
In addition to being a major crude oil export region, the Middle East is also an important global diesel production hub.
In 2025, Gulf countries - including Saudi Arabia, the United Arab Emirates, Kuwait, Bahrain and Oman - will export about 1.4 million barrels of diesel per day.
By September 2026, that number had dropped to about 670,000 barrels per day.
This significant drop in supply is mainly due to the war between the United States and Iran affecting the flow of refined diesel exports from Gulf countries through the Strait of Hormuz (Strait of Hormuz).
Iranian attacks on oil tankers and U.S. blockades of Iranian ports have severely disrupted shipping flows in the waterway.
While crude oil flows through the waterway returned to near pre-war levels last month, in part because the U.S. Navy helped protect shipping, refined diesel flows from the Middle East remain well below pre-war levels, according to estimates from ship tracking companies.
So which conflict is more responsible?
Data shows that the conflict with Iran has had a greater impact on the decline in global diesel exports than the war in Ukraine.
Russia's exports fell by about 670,000 barrels per day, compared with a decrease of about 810,000 barrels in the Middle East.
However, analysts emphasize that the impact of both is very significant.
Professor Paul de Leeuw, director of the Energy Transition Institute, Robert Gordon University in Scotland, told BBC Fact Check: "The US-Iran conflict will have a major impact on global energy markets in 2026, but the ongoing Russia-Ukraine conflict is now further exacerbating this pressure as it shuts down Russian refineries."
His sentiments were echoed by oil analyst Rory Johnson at commodities research firm Commodity Context. Johnson said the attack in Ukraine "brought the pain of the war to Russia itself and largely pushed the world's second-largest diesel exporter out of the market."
Additional reporting: Nicholas Barrett, Joshua Cheetham
