On April 13, U.S. Forces began enforcing a naval blockade of Iranian ports in the Strait of Hormuz after President Trump vowed to block any ship attempting to enter or leave the waterway, a move aimed at tightening economic pressure on Tehran amid stalled diplomatic talks.
The blockade, which U.S. Central Command says halted all economic trade and costs Iran $435 million per day, came into effect during a two-week ceasefire between the U.S. And Iran, following failed peace negotiations. Despite the naval presence, satellite imagery reviewed by The Washington Post shows five empty tankers arrived at Iranian ports in recent days and began loading millions of barrels of oil, indicating ongoing activity at the ports themselves.
Maritime intelligence firm Windward AI reported that as of April 13, at least 11 tankers carrying approximately 20 million barrels of Iranian oil were positioned offshore Malaysia in a ship-to-ship transfer hub, using offshore networks to bypass direct transit through the Strait. These vessels are likely awaiting counterpart ships for offloading or preparing for onward movement, allowing Iran to continue oil exports without entering the blocked zone.
Meanwhile, TankerTrackers.com noted that Iran continues to load and dispatch tankers from its floating storage vessels in the Gulf of Oman, which were already positioned outside Iranian waters when the blockade began. These ships have enabled the sale of another nine million barrels of crude oil, valued at approximately $900 million, to foreign buyers unaffected by the port restrictions.
Despite U.S. Claims of an airtight blockade, the Navy acknowledged turning back 13 Iranian tankers attempting to reach or leave port, while two U.S.-sanctioned tankers in ballast condition were observed entering Iranian waters with their Automatic Identification Systems active, suggesting some vessels are evading detection.
For more on this story, see Trump Blocks Hormuz Strait: Escalating Conflict and Oil Price Drop.
The Treasury Department has warned banks in China, Hong Kong, the UAE, and Oman that they could face secondary sanctions if they continue processing payments for Iranian oil, describing the financial pressure as equivalent to kinetic military action. This marks a shift from last month’s waiver of sanctions on already-afloat Iranian oil, which had been intended to ease global supply shortages.
U.S. Officials say the intensified pressure aims to gain leverage in ongoing diplomatic talks, which are progressing toward a second direct meeting between American and Iranian officials. The Trump administration secured a 10-day ceasefire from Israel to pause its incursion into Lebanon, a move described as meeting a key Iranian demand and facilitating renewed negotiations.
How is Iran managing to export oil despite the U.S. Port blockade?
Iran is using offshore ship-to-ship transfers near Malaysia and floating storage vessels in the Gulf of Oman that were already outside Iranian waters when the blockade began, allowing it to load and sell oil without entering the restricted zone.
What evidence shows the blockade is not completely stopping Iranian oil movement?
Satellite imagery shows tankers loading at Iranian ports, Windward AI tracks 20 million barrels offshore Malaysia, and TankerTrackers.com confirms nine million barrels sold from floating storage, while two sanctioned tankers were seen entering Iranian waters with AIS active.
What is the U.S. Doing to target Iran’s oil revenue beyond the naval blockade?
The Treasury Department has sent warnings to banks in China, Hong Kong, the UAE, and Oman, stating they could face secondary sanctions for processing Iranian oil payments, which officials describe as the financial equivalent of military action.
