Energy and insurance specialists have cast doubt on Donald Trump's plan to insure tankers in the Gulf, complicating efforts to curb the oil price surge triggered by the Iran war. Trump tasked the Development Finance Corporation to provide insurance to vessels sailing through the Strait of Hormuz, where flows have slowed dramatically since the outbreak of conflict.

New research from JPMorgan shows the DFC has access to just $154bn of the $352bn needed to underwrite the 329 oil vessels in the region. Private insurers have told ship owners they will cancel policies and sharply increase prices as the Middle East conflict escalates. Insurance market figures doubt the DFC's balance sheet is large enough to underwrite the values at risk or that the agency would be nimble enough to help idling tankers secure cover in the coming days.

The DFC is only allowed to have a maximum total liability of $205bn through 2031, of which it had used $51.5bn by the end of 2025. Raising the cap would require an act of Congress. The figures will undermine the president's efforts to instill confidence in shipping executives who have been reluctant to send vessels through the strait, the chokepoint for about 20mn barrels a day of oil supply — about a fifth of the world's demand.