Iran’s September Oil Exports Reach a 2025 High, Underscoring Sanctions Enforcement Gaps

Iran’s oil exports in September 2025 reached their highest monthly level of the year, according to TankerTrackers, highlighting the continued shortcomings of international sanctions enforcement.

Tehran shipped an estimated 63.8 million barrels during the month, averaging 2,127,714 barrels per day (bpd). Priced at a 5-10 percent discount to Brent crude, September exports likely generated between $3.9 and $4.2 billion in gross revenue, hard currency that supports Tehran’s finances and external activities.

Who Are the Customers and Enablers?

A single buyer, China, bought up the overwhelming majority of crude imports from Iran. It accounted for 87.35 percent of observed shipments (approximately 1,858,596 bpd). The remaining volumes transited through the United Arab Emirates (101,876 bpd), Malaysia (83,491 bpd), “unknown” destinations (65,509 bpd), and Indonesia (18,242 bpd). These routes are consistent with established transshipment and blending practices designed to obfuscate the origin of oil prior to refining.

At sea, 49 tankers were involved in September movements, operating under flags from 14 jurisdictions, including Iran, Comoros, Curaçao, Guyana, Benin, Gambia, Panama, Guinea, San Marino, Hong Kong, Tonga, Jamaica, Barbados, and Palau. Ports receiving the Iranian oil were Huizhou and Dongying in China,  Port Klang in Malaysia, Fujairah, Jebel Ali, and Hamriya in the United Arab Emirates, and Karimun in Indonesia.

Implications of Increased Oil Exports

Three conclusions follow from these data. First, buyer concentration creates policy leverage. With nearly nine in 10 barrels ultimately destined for China, calibrated enforcement targeting Chinese refiners, traders, ports, and financial intermediaries can materially affect Tehran’s export capacity and revenues.

Second, maritime services remain the principal chokepoint. Insurance, classification, flagging, and trade finance enable this trade; constraining these services raises risk and cost for participants.

Third, despite the framework of U.S. economic pressure, Iran’s observed exports, averaging roughly 1.8 million bpd in 2025, exceed levels recorded during the first Trump administration’s maximum pressure campaign, reflecting the evolution of a parallel ecosystem of shadow tonnage, permissive registries, and non-transparent financing.

U.S. Must Strengthen Sanctions Enforcement

U.S. policy should address the decline of sanctions enforcement in four key ways.

First, the Trump administration should tighten pressure on maritime services where risk is concentrated. Regulators should expand scrutiny and designations for flag registries, ports, tanker operators, and protection and indemnity providers linked to Iran-affiliated tonnage. Washington should prioritize engagement with jurisdictions whose flags and ports the implicated vessels repeatedly use. The United States should impose escalating penalties on repeat offenders.

Second, enforcement should focus on the Chinese entities integral to this trade: refiners, commodity traders, port operators, and banks, especially those with international footprints and exposure to dollar/euro clearing, global insurance, and capital markets. In parallel, authorities should map and disrupt intermediary traders, storage providers, and port facilities in the United Arab Emirates, Malaysia, and Indonesia that facilitate the laundering of origin and documentation.

Third, the Trump administration should align financial controls with physical interdiction. Customs, maritime, and financial supervisors should coordinate to restrict insurance and reinsurance, deny access to dollar/euro clearing, and limit trade finance for entities implicated in the movement of Iranian barrels. Joint shipping-and-banking advisories should detail recurrent patterns of falsified paperwork, AIS manipulation, and STS operations to guide compliance programs and elevate transaction costs for facilitators.

Fourth, the Trump administration should raise the cost of noncompliance using all lawful tools. Where legally justified, authorities should seize tankers transporting Iranian oil in violation of sanctions, auction the cargoes, and allocate proceeds to initiatives that empower the Iranian people, such as secure communications and satellite internet access. Washington should also treat entities tied to the Islamic Revolutionary Guard Corps the same as facilitators of other U.S.-designated terrorist organizations, such as ISIS and al-Qaeda.

September’s 2.13 million bpd is not merely a statistical peak; it is evidence of where enforcement is weakest. The concentration of buyers and the centrality of maritime services provide a clear roadmap. If policymakers act at these nodes, consistently and in coordination, Washington can curtail Tehran’s ability to monetize sanctioned oil.

Saeed Ghasseminejad is a senior Iran and financial economics advisor at the Foundation for Defense of Democracies (FDD). For more analysis from Saeed and FDD, please subscribe HERE. Follow Saeed on X @SGhasseminejad. Follow FDD on X @FDD and @FDD_Iran. FDD is a Washington, DC-based, nonpartisan research institute focusing on foreign policy and national security.