Iran has run out of its offshore crude oil reserves, according to energy-data firm Kpler, removing a financial lifeline that helped the regime continue selling oil to China during its war with the United States and Israel.

Kpler analysts said the stockpile was depleted by mid-October, although other energy-tracking organizations estimated that some supplies remained. The depletion comes as a U.S. naval blockade restricts Iran’s ability to export oil and collect revenue from its largest source of foreign currency.

“There’s no more oil to discharge to China anymore,” said Homayoun Falakshahi, Kpler’s head of crude-oil analysis.

Oil sales account for approximately 30% to 40% of Iranian government revenue, making the loss of the offshore reserves a significant setback for Tehran as it struggles with soaring inflation, shortages and a weakening currency.

U.S. Central Command said the blockade had cost Iran at least $25 billion in oil revenue, limiting the regime’s ability to rebuild damaged industrial facilities and replenish its weapons stockpiles. Adm. Brad Cooper, the command’s leader, said the U.S. campaign had imposed “devastating costs” on Iran’s security apparatus.

Meanwhile, oil shipments from other Middle Eastern countries have surpassed prewar levels as U.S. protection has helped non-Iranian tankers navigate the Strait of Hormuz, according to reporting by The Wall Street Journal.

Iran accumulated its offshore reserves through a network designed to evade international sanctions. Tankers transported crude to waters near Malaysia and Singapore, where the oil was transferred between vessels before being delivered to Chinese refineries. The system allowed Tehran to store large quantities of oil at sea while making shipments more difficult to track.

At the start of the war in February, Iran held approximately 135 million barrels of oil in overseas storage, according to Kpler. Following a surge in oil prices, that stockpile may have been worth at least $10 billion.

The reserves began declining rapidly after Washington imposed a naval blockade in April. Iran replenished its supplies when the blockade was lifted during peace negotiations in mid-June, but the stockpile began shrinking again after restrictions resumed in mid-July.

Kpler estimated that the replenished reserves peaked at nearly 90 million barrels before falling below 1 million barrels by October 5 and eventually reaching zero.

Other trackers confirmed a steep decline but differed on how much oil remained. Emma Li, an analyst at Vortexa, estimated that approximately 6 million barrels of Iranian crude were still near Singapore as of October 9. She said Chinese refineries were increasingly turning to alternative suppliers in Brazil and West Africa.

United Against Nuclear Iran, an advocacy group that monitors Tehran’s oil trade, estimated that Iranian oil exports fell to nearly zero in August and September. The organization also placed Iran’s remaining floating reserves in Southeast Asia at 10 million barrels or less by early October.

Charlie Brown, a researcher with the group, said the available evidence suggested Iran’s reserves were approaching exhaustion, although he could not independently confirm that they had been completely depleted.

The loss of offshore oil supplies threatens to intensify Iran’s economic problems, though the regime may continue receiving payments for crude sold earlier. Analysts said Chinese purchases typically take about two months to settle, meaning some revenue could still reach Tehran even as new shipments stall.

Iran has also tried to circumvent the restrictions by storing crude in aging domestic tanks and transporting oil overland to neighboring countries. However, those methods cannot match the volume previously moved by sea.

The Iranian currency has lost approximately one-third of its value against the U.S. dollar since early July, adding to inflation and the financial strain facing households and businesses.

Iman Nasseri, senior vice president for the Middle East and Asia at FGE NexantECA and a former researcher for Iran’s oil ministry, said the blockade was having an effect. He cautioned, however, that Iran’s government had survived previous economic crises and that the long-term consequences remained uncertain.

Iranian officials have rejected claims that the economy is collapsing. Central bank Gov. Abdolnaser Hemmati said at an International Monetary Fund meeting in Bangkok last week that the country had demonstrated resilience and described claims of an economic collapse as an illusion.

The depletion of the offshore stockpile nevertheless leaves Tehran with fewer options to sustain oil exports, maintain foreign-currency inflows and finance its government as the U.S. blockade continues. Analysts say the growing economic pressure could push Iran toward renewed nuclear negotiations or fuel domestic unrest, although neither outcome is guaranteed.