US weighs halting tankers at sea to squeeze Iran oil trade

The administration of US President Donald Trump is considering a plan to inspect Iranian oil tankers under an international accord designed to curb the spread of weapons of mass destruction, six sources familiar with the matter told Reuters.

The move would be part of US President Donald Trump’s renewed "maximum pressure" campaign, aimed at cutting Iran’s oil exports to zero.

More than half of the tankers sanctioned three days ago by the United States for carrying Iran's oil have ceased operations outside Chinese or Iranian terminals, an investigation by Iran International last month revealed.

Since returning to office, Trump has imposed fresh sanctions targeting companies and the so-called shadow fleet of older oil tankers transporting Iranian crude without Western insurance.

Sources said the administration is exploring ways for allied countries to stop and inspect vessels in key maritime chokepoints, including the Malacca Strait in Asia.

“You don’t have to sink ships or arrest people to have that chilling effect that this is just not worth the risk,” one source said. Another added: “The delay in delivery … instills uncertainty in that illicit trade network.”

The US is examining whether the inspections could be carried out under the Proliferation Security Initiative, signed by over 100 countries, a 2003 multinational framework aimed at stopping the trafficking of weapons of mass destruction.

John Bolton, who helped establish the initiative, said: “It would be fully justified” to use it against Iranian oil shipments, arguing that Tehran relies on crude revenue to fund nuclear activities and militant groups.

Two sources said the White House National Security Council is reviewing the proposal, but it remains unclear if Washington has approached any governments to gauge their willingness to participate. The National Security Council declined to comment as reported by Reuters. Iran's oil and foreign ministries also did not respond.

Iranian President Masoud Pezeshkian, addressing parliament on Sunday, acknowledged Trump’s latest sanctions, saying Iran’s tankers now face uncertainty in unloading their cargo. Iran has previously retaliated when its oil shipments were seized.

In 2023, the US tried to interdict two Iranian oil cargoes under Biden, prompting Iran to seize foreign vessels, including one chartered by Chevron.

Despite past US sanctions, Iran’s oil exports brought in over $50 billion annually in recent years, largely from sales to China. Meanwhile, European countries have raised concerns about environmental risks from tankers but have taken little action to inspect Iranian oil shipments.

Since early September, Iran’s national currency, the rial, has lost half of its value due to military and geopolitical setbacks in the region and Trump’s election, as he has pledged to significantly cut Tehran’s oil exports.