Twenty percent of the world’s oil passes through the Strait of Hormuz. For nearly three months, barely any of it has moved. The consequences are now rewriting Western sanctions policy.

The UK announced Tuesday it is loosening sanctions on Russian oil refined into diesel and jet fuel in third countries — effectively allowing imports from India and Turkey, which process Russian crude. The waiver, effective Wednesday, also eases restrictions on maritime transport of Russian liquefied natural gas.

The proximate cause is the effective blockade of the Strait of Hormuz since the US-Israel war with Iran began on February 28. BBC Verify analysis showed only a handful of ships have passed through since a temporary ceasefire was announced April 8, compared to roughly 138 vessels on a normal day. Oil prices jumped from $73 to $126 a barrel at one point — the highest since Russia’s 2022 invasion of Ukraine — and remain volatile.

British motorists are paying the price. Unleaded petrol hit 158.5p per litre on May 19, the highest since the war began, according to the RAC. Filling a typical family car with petrol now costs roughly £14 more than before the conflict; diesel is £27 more. The RAC expects unleaded to reach at least 160p per litre in the coming weeks unless oil prices drop significantly.

European jet fuel prices more than doubled after the war started and remain roughly 50% above pre-war levels. Airlines have cancelled flights and raised fares. The International Energy Agency warned in April that Europe had “maybe six weeks of jet fuel left.”

The sanctions unwind

Since October, the UK had banned imports of diesel and jet fuel refined from Russian crude in third countries. For years, Britain led international efforts to put economic pressure on Russia over its war in Ukraine. Now it is opening the valve.

The UK’s move mirrors a similar decision by the United States, which has repeatedly extended a sanctions waiver allowing the purchase of Russian oil already loaded on vessels at sea. Treasury Secretary Scott Bessent called it a “short-term measure” aimed at “stability in global energy markets.” The logic is consistent in both capitals: when energy prices spike enough to threaten domestic political consequences, market stability takes precedence over sanctions enforcement.

The timing is awkward. On Tuesday, the UK signed a G7 statement reaffirming its “unwavering commitment” to impose “severe costs” on Russia. On Wednesday, it began unwinding the mechanisms designed to impose those costs. A government spokesperson said the UK had simultaneously “introduced a range of new prohibitions” and remained “committed to strengthening our sanctions on Russia to degrade its ability to wage war in Ukraine, whilst protecting critical supply chains and maintaining market stability.”

The new rules for processed oil products will be of “indefinite duration,” subject to periodic review. The LNG transport licence runs until January 1.

The cost to Ukraine

Allies have been blunt. French President Emmanuel Macron said the Hormuz shutdown “in no way” justified lifting sanctions on Russia. Ukrainian President Volodymyr Zelensky was more direct: “Every dollar paid for Russian oil is money for the war.”

Zelensky said more than 110 tankers carrying Russian oil in breach of sanctions were at sea, holding over 12 million tonnes of crude valued at $10 billion that “can once again be sold without consequences.” French Finance Minister Roland Lescure stressed that “Russia mustn’t be getting benefits from what’s happening in Iran” and Ukraine should not become “collateral damage.”

A brittle architecture

The broader issue is one governments prefer not to discuss. Sanctions are presented as durable instruments of economic pressure — levers that can be pulled and held indefinitely. In practice, a single geopolitical crisis in a different theater forced partial reversals within weeks.

JP Morgan estimates global oil prices will remain above $100 a barrel for the rest of 2026, even if the Strait of Hormuz reopens. Every extension of a waiver makes the next one easier to justify. Every month of higher pump prices erodes the political will to maintain restrictions voters feel directly.

The architecture of Western sanctions on Russia was built on the assumption that governments could absorb the economic costs of enforcement. Iran’s blockade tested that assumption, and it did not hold. The question now is how much further sanctions erode — and whether any future sanctions regime will be credible enough to deter its targets.

Sources