1. Sanctions on oil tankers and shipping companies transporting Iranian crude oil
1. Block oil tanker operating capacity
The United States has included tankers involved in transporting Iranian crude oil on the "Specially Designated Nationals and Blocked Persons List" (SDN List). For example, the "CH Billion" and "Star Forest" tankers, which are set to transport Iranian crude oil from Dalian, China in January 2025, are unable to use the dollar trading system after being sanctioned. Relevant shipowners, insurance companies, and port service providers refuse to offer services due to fear of secondary sanctions.
Subsequent sanctions also involve several oil tankers (such as the NICHOLA and NATALINA 7), which, once sanctioned, will have their global navigation and docking permissions restricted, leading to an inability to unload normally.
2. Cut off the shipping support network
The U.S. Treasury Department has imposed sanctions on 19 shipping entities, including Hong Kong's Astrid Menks Limited. These companies are accused of forming a "shadow fleet" to evade tracking by shutting off vessel positioning signals, frequently changing flags and names. However, after the sanctions, their dollar accounts were frozen, disrupting the international shipping cooperation chain and indirectly hindering unloading operations.
2. Sanctions on China's crude oil storage terminals and refineries
1. Directly block storage facilities
In March 2025, the U.S. Department of State placed the Huizhou Daya Bay Huaying Petrochemical Terminal on the SDN list under the justification of "receiving Iranian crude oil." The terminal's assets were frozen due to the storage of 1 million barrels of Iranian crude oil unloaded from the sanctioned tanker NICHOLA, forcing international partners to terminate their business dealings with it, effectively paralyzing the terminal's unloading capacity.
2. Crack down on the "teapot oil refinery" procurement chain
The United States has imposed sanctions for the first time against independent refineries in China, such as Shandong Luqing Petrochemical, accusing them of circumventing the dollar system by purchasing Iranian crude oil through RMB settlements. The sanctions include freezing the companies' dollar accounts, prohibiting U.S. entities from trading with them, and threatening secondary sanctions on third-party financial institutions, forcing the refineries to be unable to pay unloading fees or receive crude oil.
III. Use financial hegemony to exert pressure
1. Dollar trading restrictions
Entities under sanctions that use US dollars for settlement will trigger monitoring and interception by the US financial system. For example, the Huaying Petrochemical Terminal was directly sanctioned for involving US dollar transactions, while Shandong Luqing Petrochemical partially mitigated risks through RMB settlement, but still faced impacts on unloading processes due to restrictions on the USD business of associated shipping companies.
2. Long-arm jurisdiction deters third parties
The United States is using threats of secondary sanctions to force international port service providers (such as fuel suppliers and freight forwarders) to refuse support for vessels involved with Iranian oil. For example, if a sanctioned tanker attempts to dock at a Chinese port, it may face fuel supply interruptions or denial of navigation services, leading to the inability to complete unloading operations.
4. Geopolitics and Economic Games
The deeper purpose of the U.S. sanctions is to curb the impact of China-Iran energy cooperation on the hegemony of the U.S. dollar. China has partially broken the blockade through a "shadow fleet" and a RMB settlement system (such as using Beidou navigation to replace GPS and RMB oil trading), but the U.S. has further created legal and business risks by upgrading the sanctions list and offering rewards for the capture of Chinese corporate executives (such as a reward of 109 million yuan for four Chinese citizens), forming a deterrent cycle of "being sanctioned upon unloading."
Summary
The United States, through a combination of "entity sanctions + financial blockade + long-arm jurisdiction," attempts to cut off the logistics, capital, and information chains of Iranian crude oil entering Chinese ports. Although China has taken countermeasures through non-U.S. dollar settlements and technical means, the U.S. sanctions have still significantly increased the legal risks and operational costs of unloading, leading to some crude oil being stranded or forced to be rerouted.