Average US fuel prices have crossed $4 a gallon for the first time in four years, piling pressure on drivers as Donald Trump’s war on Iran continues to boost oil markets.

The nationwide average climbed to almost $4.02 on Tuesday, according to AAA data, capping an extraordinary rise from $2.98 just a month ago. The fuel price last reached this high in August 2022.

On the west coast, many drivers filling up cars and trucks are grappling with prices far higher than the US average. In California, the average is $5.89 a gallon; in Washington state, the average is $5.35.

Prices at the pump have historically proven costly for the White House. Trump faces his biggest electoral test of his second term later this year, with Republican control of Congress in the balance before November’s midterm elections.

Oil prices have surged since the US and Israel launched their war on Iran, with Brent crude, the global benchmark, hitting $115.48 a barrel.

As concern mounted over the impact of higher oil prices over a sustained period, the US president has repeatedly tried to play down the impact – and even argue that the country will benefit as a whole.

“The United States is the largest Oil Producer in the World, by far, so when oil prices go up, we make a lot of money,” Trump wrote on his Truth Social platform in March.

Asked by a CBS News reporter about the sharp rise in US fuel prices on Tuesday, Trump replied: “They’ll drop when we leave, when it’s over.”

The president plans to withdraw US forces from the war “at some point”, he told the network. “Not quite yet,” added Trump. “But countries have to come in and take care of it. Iran has been decimated, but they’re going to have to come in and do their own work.”