US president Donald Trump hosted a grand welcome for Chinese president Xi Jinping but in the background of this fanfare, an investigation by the Wall Street Journal has shown how China has been supporting Iran militarily in its war against the US.When the US and Iran agreed to a temporary truce this summer, China was quick to highlight its diplomatic role.Beijing said its foreign ministry had made dozens of calls to help ease tensions, while Xi Jinping had personally offered suggestions aimed at ending the conflict.But on the very day the truce was signed, a Chinese aircraft landed in Tehran carrying electronics for Iran’s ministry of defense. According to Iranian customs records analysed by WSJ, some of the components could be used in drone systems and missile guidance equipment.This shipment was also not an isolated incident, as WSJ found records of around 1,300 shipments of dual-use components from China to Iran’s defence ministry through the end of June. Two days after the truce-day delivery, more than a dozen additional shipments arrived carrying parts worth over $6 million that could be used in drones.With Xi currently in Washington for talks with Trump, China’s relationship with Iran has emerged as an uncomfortable issue sitting beneath the official summit agenda of trade, artificial intelligence and Taiwan.
The supply line to Iran
WSJ’s investigation, based on Iranian customs records, US officials and people familiar with the transactions, describes a growing air bridge between China and Iran.Records covering January 2025 through June 2026 show thousands of shipments to Iran’s defence ministry and Iranian companies. They included GPS tracking equipment, electric motors and aircraft-engine components. Many shipments carried references to Article 119 of Iranian customs regulations, which provides tariff exemptions for defence imports.The flow intensified after the US Navy restricted Iranian maritime trade.Iranian airline Mahan Air, which is under US sanctions, increased flights from Beijing, Shanghai and Guangzhou to Tehran from four a week in early March to about 27 a week by late April, according to FlightRadar24 data.By the first week of September, Mahan Air had flown 39 times from China to Iran, roughly twice its prewar level. Many of those flights appeared to be focused on cargo rather than passengers, WSJ reported.Researchers tracking Iranian trade told WSJ that some of the Chinese suppliers involved are little-known companies working with Iranian importers.Kate Koren, deputy director of the economics programme at the Center for Strategic and International Studies, told WSJ that some of the components being traded are known to be used in Iran’s Shahed drones. A forthcoming CSIS report, she said, identified Chinese companies publicly advertising sensitive electronics this year.The report also stated that Chinese companies have supplied Iran with chemical materials including sodium perchlorate, which can be used to make propellant for ballistic missiles. US authorities have also sanctioned Chinese and Hong Kong-based companies over alleged efforts to help Iran acquire weapons and military equipment.In one case, US officials said a procurement network tried to obtain Chinese shoulder-fired missile systems for Iran and route them through Belarus to conceal the Iranian end-user. The attempted transaction was unsuccessful, according to those officials.
China’s oil lifeline; and Washington’s dilemma
The relationship is not one-sided but rather symbiotic.China has become Iran’s largest oil customer, providing Tehran with a major source of revenue despite US sanctions. Chinese front companies and financial networks have helped facilitate Iranian oil transactions and move money through China’s financial system.Iran and China deepened their relationship after the Trump administration’s 2018 “maximum pressure” campaign. The two countries signed a 25-year strategic cooperation pact in 2021, while China became the dominant buyer of Iranian crude.US lawmakers have said China buys more than 80% of Iran’s crude exports. More recently, a US Senate foreign relations committee statement citing Treasury figures put the share at about 90%.Washington has responded with hundreds of sanctions against Iranian and Chinese entities since the war began, including companies accused of helping Tehran obtain weapons, components or revenue.Yet the Trump administration has so far been cautious about directly confronting Beijing, especially after the earlier tariff confrontation exposed China’s leverage.People familiar with discussions inside the administration told WSj that Trump had made maintaining good relations with Xi a priority ahead of the summit. Some senior officials have consequently played down the significance of Chinese assistance to Iran.That approach has created disagreement within Washington, with defence secretary Pete Hegseth blaming China for enabling Iran, a claim Trump rejected stating, “I trust them.”
The satellite trail
According to US officials cited by WSJ, Iran used satellite imagery obtained from Chinese entities before and after a July 17 strike that killed three US troops.The Trump administration had already sanctioned three Chinese satellite-imagery companies in May, saying the companies had provided information that could help Iran target US forces.That has intensified pressure within Washington to confront Beijing.In late August, Trump and Treasury Secretary Scott Bessent launched “Operation Economic Outcast”, aimed at cutting the economic networks sustaining Iran. The US subsequently sanctioned a China-owned oil tanker and Chinese companies and individuals accused of helping Iran obtain critical components.But the administration did not impose major new sanctions directly on Chinese financial institutions.Meanwhile, Iranian oil has continued reaching China.Kpler estimated that around four million barrels were delivered to China in the week after Operation Economic Outcast began.And despite sanctions and the wider conflict, Mahan Air continues to fly to China.
Contradiction at the heart of the Xi-Trump summit
Xi’s arrival in Washington now carries two very different messages.China wants to be seen as a country capable of brokering peace and stabilising the Middle East. Beijing has publicly rejected attempts to associate it with the conflict and says it opposes unilateral US sanctions and supports diplomatic efforts to end the fighting.At the same time, WSJ’s investigation found evidence of continued Chinese trade with Iran involving components that can have military applications.Chinese officials have said Beijing strictly regulates exports of dual-use goods and rejects allegations that it is deliberately supporting the conflict.The tension is therefore not simply about whether China supports Iran. It is about how far Beijing is willing to go, and how far Washington is willing to push back, while both sides try to preserve a broader relationship.The same China that Trump wants to keep close for trade and strategic reasons is deeply embedded in the economic and supply networks helping Iran sustain itself.And that makes Iran an awkward third presence at a summit ostensibly about America and China.
