When the war began in February, Iran had about 135 million barrels of crude stored on tankers overseas, most of it parked off the coasts of Malaysia and Singapore. It was worth at least $10 billion, and it was Iran's lifeline to China.

By October 5, there was less than 1 million barrels left.

"There's no more oil to discharge to China anymore," said Homayoun Falakshahi, who heads crude oil analysis at the ship-tracking firm Kpler.

That stockpile was the heart of Iran's "shadow fleet," aging tankers that transferred oil from ship to ship in Southeast Asian waters to hide where it came from, then delivered it to small Chinese refineries. For years it let Tehran sell oil around the world despite U.S. sanctions.

President Trump shut it down.

The U.S. Navy first blockaded Iran's oil exports in April. Washington lifted the blockade in mid-June during peace talks, and Iran used the pause to refill its floating stockpile to nearly 90 million barrels. The talks went nowhere, and in mid-July the blockade came back.

No new Iranian crude has crossed the blockade line since July 14, according to the watchdog group United Against Nuclear Iran. Tehran was left selling off its floating reserve with no way to replace it. In September, for the first time in a tracking record going back to 2013, Iran shipped no crude at all. Twenty empty Iranian tankers drifted off the coast of Sri Lanka, unable to get back home through the blockade.

Adm. Brad Cooper, the head of U.S. Central Command, says the blockade has cost Iran at least $25 billion in oil revenue and has "imposed devastating costs on Iran's security apparatus." Reports from CENTCOM say Iran's Revolutionary Guard is now struggling to pay its own troops.

That's a big problem for a regime that runs on oil money. Oil accounts for 30% to 40% of Iran's government revenue, and that money funds the Revolutionary Guard, its proxy militias, and its weapons programs. Iran's currency has lost about a third of its value against the dollar since early July. The International Monetary Fund now projects Iran's economy will shrink 7.6% this year, after shrinking last year too.

The Treasury Department has been squeezing from the financial side. Under a sanctions campaign called Operation Economic Outcast, it has targeted the companies, middlemen, and vessels that keep Iranian oil moving. "Our objective," Treasury Secretary Scott Bessent said, "is to sever every economic lifeline that sustains this tyrannical regime until Tehran stands alone."

For years, critics warned that cutting off Iran's oil would send global prices through the roof. The war did drive prices up when it began, but while Iran's exports have fallen to nothing, America's allies in the Gulf have picked up the slack. CENTCOM says more than 1 billion barrels of crude have moved from Gulf partners through the Strait of Hormuz during the blockade.

"Iran has exported zero barrels," Cooper said, "thanks to our ironclad blockade."

By late September, crude exports from the region's major producers averaged 18.3 million barrels a day, the highest since the war began, led by Saudi Arabia and the United Arab Emirates.

Tehran insists it's fine. Iran's central bank governor told an IMF meeting in Bangkok that "the claim that Iran's economy is collapsing is nothing more than an illusion." His own currency, his own export figures, and the IMF's forecast all say otherwise.

Iran's new supreme leader, Mojtaba Khamenei, took power in March after his father, Ayatollah Ali Khamenei, was killed in an early strike of the war. So far, he has refused to make a deal. He's now running a government whose oil, its main source of money, can't get past the U.S. Navy.

In February, Iran had 135 million barrels on the water. By October 5, it had less than 1 million.