What Happened
- Despite the Strait of Hormuz effectively being shut to most commercial shipping following the US-Israel attack on Iran, approximately 90 ships have crossed the strait carrying Iranian crude oil, almost exclusively destined for China
- Iran has exported at least 11.7 million barrels of crude through Hormuz since hostilities began on February 28, 2026, while loading approximately 1.5 million barrels per day in March
- China has been the exclusive buyer of Iranian oil under Western sanctions; China absorbed approximately 1.25 million barrels per day, compared to Iran's export peak of 2.16 million bpd in February 2026 — the highest since July 2018
- Iran reportedly allows Chinese-flagged and Chinese-chartered vessels selective passage through Hormuz while blocking other nationalities, using oil exports as a strategic lever to retain Chinese economic and diplomatic support
- The US "maximum pressure" campaign, relaunched in February 2025, sought to drive Iranian oil exports to zero including to China, but has not succeeded in cutting the flow
Static Topic Bridges
Sanctions Regimes and the Shadow Fleet
Western sanctions on Iran are primarily enforced through the US Office of Foreign Assets Control (OFAC) under the Iran Sanctions Act and successive Executive Orders, supplemented by European Union autonomous measures. However, enforcement against sovereign third-country buyers (particularly China) is inherently limited because US secondary sanctions — which penalise non-US entities for doing business with Iran — create diplomatic friction rather than physical blockade. Iran has adapted through a "shadow fleet" of aging tankers that obscure their activity: disabling tracking transponders (Automatic Identification System, AIS), spoofing GPS locations, conducting ship-to-ship transfers in international waters, and operating under multiple flag registrations. By 2025, Iranian crude exports to China were valued at approximately $31.2 billion, with oil revenue accounting for roughly 45% of Iran's government budget.
- OFAC sanctioned over 875 persons, vessels, and aircraft under the maximum pressure campaign in 2025; a further dozen shadow fleet vessels were sanctioned in late February 2026
- China and Russia blocked a US-drafted UN Security Council briefing on Iran sanctions in March 2026, rendering multilateral enforcement mechanisms inoperable
- Shadow fleet voyage times have shortened from 85–90 days to 50–70 days through optimised routing and mid-ocean ship-to-ship transfers
Connection to this news: The continued Iran-China oil flow during active hostilities demonstrates that secondary sanctions, without physical interdiction, cannot cut a motivated bilateral relationship — particularly when the buyer is a permanent UN Security Council member.
China-Iran Bilateral Relations and Energy Dependence
China and Iran signed a 25-year Comprehensive Cooperation Agreement (CCA) in 2021, covering trade, investment in Iranian infrastructure, and continued Chinese purchases of discounted Iranian oil. The agreement is part of China's broader Belt and Road Initiative (BRI) strategy and gives Tehran a guaranteed buyer insulated from Western financial systems. China pays for Iranian oil largely through yuan-denominated transactions and barter arrangements, bypassing SWIFT. For China, Iranian oil serves two purposes: it is substantially discounted compared to market price (estimated 10–20% below benchmark), and it helps China diversify away from Gulf Arab suppliers who maintain closer relationships with the US.
- Iran exported 2.16 million barrels per day in February 2026, the highest since July 2018 and the peak of JCPOA-era sanctions relief
- China has been building strategic oil reserves; as of the crisis onset, China was absorbing approximately 1.25 million bpd of Iranian crude
- The 25-year CCA (2021) commits China to $400 billion in investment in Iranian infrastructure (transport, ports, telecoms, banking) in exchange for discounted energy
Connection to this news: The CCA framework and yuan payment architecture explain why neither diplomatic pressure nor OFAC sanctions can easily interrupt the Iran-China oil corridor — the transaction infrastructure deliberately bypasses US-controlled financial plumbing.
Iran's Closure of an International Strait: Legal Dimensions
Under UNCLOS Articles 37–44, the right of transit passage through international straits cannot be suspended by coastal states. Iran, however, has neither ratified UNCLOS nor recognised Hormuz as an international strait subject to the transit passage regime — instead applying its own 1993 national maritime law which only recognises innocent passage. Iran's closure is therefore legally contested but practically enforced. The 2026 crisis is the first time Iran has actually implemented closure (earlier closures were only threatened), forcing the international community to confront the gap between treaty rights and enforcement capacity.
- Innocent passage (UNCLOS Article 19) applies to territorial seas and grants less permissive rights than transit passage — it can be limited on security grounds, whereas transit passage cannot be suspended at all
- Iran controls the northern coast of the strait; Oman controls the southern coast (including the Musandam peninsula)
- The US Fifth Fleet is headquartered at Manama, Bahrain; its ability to guarantee freedom of navigation through Hormuz is now being directly tested
Connection to this news: Iran's selective allowance of Chinese vessels — while blocking others — is itself a legal novelty, creating a discriminatory passage regime that has no recognised basis in international maritime law.
Key Facts & Data
- Iran's February 2026 oil exports: 2.16 million barrels per day — highest since July 2018
- Chinese absorption: ~1.25 million barrels per day through crisis period
- Total Iranian oil shipped through Hormuz since Feb 28, 2026: at least 11.7 million barrels
- Value of Iranian crude to China in 2025: ~$31.2 billion; ~45% of Iran's government budget
- Trump "maximum pressure" campaign relaunched: February 2025, targeting Iranian oil exports to zero
- OFAC sanctioned 875+ entities in 2025 under maximum pressure; additional shadow fleet vessels sanctioned February 2026
- China-Iran 25-year CCA signed: 2021, covering $400 billion Chinese investment