Donald Trump’s former defence secretary has warned that the US will not win its war against Iran through aerial bombardment and must “strangle” the Islamic republic’s economy to force open the Strait of Hormuz.
The US launched more strikes on Iran on Wednesday and Trump has said he will step up the attacks in the coming weeks to force the Islamic republic into a deal.
But Mark Esper, US defence chief during Trump’s first term, told the Financial Times the strategy would not change Iran’s stance and desire to “keep control of the strait”.
“I’m not confident that, if we picked up the bombing the way we did months ago and sustained it for a period of time, that that would have a big change,” Esper said.
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Trump this month declared his short-lived ceasefire with Iran to be “over” after claiming Iran violated a memorandum of understanding with the US to allow free maritime traffic through the strait while the warring parties negotiated a longer-term settlement. The flare-up in hostilities threatens to tip the Middle East back into a crisis and unleash a fresh inflationary impulse on the world economy.
Vessels freely travelled through the waterway — a sea lane for about 20 per cent of the world’s oil — before the US and Israel launched a war on Iran. Tehran largely shut the strait after the attack and traffic remains at a fraction of its pre-conflict level.
Esper told an audience of national security experts in Aspen on Tuesday that the Trump administration should apply “comprehensive” economic pressure to resolve the Hormuz dispute, which has pushed up fuel prices around the world.
“How do you pressure them?” Esper said on Wednesday. “One option is you resort to full military onslaught. The other one is you strangle them economically.”
But this would require “time, patience [and] discipline” as well as international support to be effective, he said during the panel discussion. “And the cost for us is going to be higher gas prices for a while.”
Brent crude, the international oil benchmark, has jumped 16 per cent since the start of July to about $85 a barrel as the conflict escalates. Oil industry executives and analysts warn that global crude supplies are already at critically low levels, and a more prolonged shutdown of the strait will trigger a sharp jump in crude prices that could even exceed the highs above $100 in the early phases of the war.
On Wednesday, US government energy data showed the country’s total inventory of stored crude oil fell again last week and now sits at its lowest level since 1984. Petrol prices are rising again as supplies tighten, raising the spectre of a new burst of inflation even after price growth eased in June.
Esper, who Trump sacked shortly after losing the 2020 election, also warned of the cost to the US’s military budget of a prolonged war, as well as its defence posture in the face of threats such as that from China.
US military analysts say the defence department has already run through tens of billions of dollars and years’ worth of munitions in a war that shows little sign of resolution.
“What is the cost for us in terms of readiness, munitions, stockpiles,” Esper said. “Because my big concern globally is China.”
Esper said in Aspen that he would use “two yardsticks” to measure the success of Trump’s war in Iran. One would be a return to the “status quo ante” in the Strait of Hormuz — meaning full and free maritime traffic. The second would be a nuclear deal “at least as good as — but needs to be probably better than” the pact struck by Barack Obama, which Trump scrapped.
Condoleezza Rice, who served as secretary of state for George W Bush’s administration, joined Esper on the Tuesday night panel and echoed his call for more economic pressure on Iran.
“I would not buy a nuclear agreement under any circumstances. Just let them sit there and stew in their lousy economy, where most of their A-level nuclear scientists have been killed, [and] where I believe there are deep splits in the Iranian government,” she said.
“Let’s just see what happens, because I am quite confident it’s going to be a long time before they can actually build and use a nuclear weapon.” - Copyright The Financial Times Limited 2026
