U.S. and Iran Enter 'Tit-for-Tat Blockade' at Sea...Tensions Escalate in Hormuz (Comprehensive)
by Lee Hyunwoo
by Hwang Yoonju
Published 13 Apr.2026 10:53(KST)
Updated 13 Apr.2026 13:29(KST)
"All Maritime Traffic to Iranian Ports Blocked"
International Oil Prices Top $100 in Four Trading Days
Immediately after the breakdown of ceasefire negotiations between the United States and Iran on April 11 (local time), the U.S. took steps to impose a blockade on all ports in Iran. This is a broader and more powerful sanction than blocking the Strait of Hormuz. The strategy is to choke off the entire import and export network, thereby crippling Iran’s economy. Iran, faced with a sudden cut-off of wartime funding, immediately protested. Amid rising tensions, international oil prices surged back to the $100-per-barrel mark. There are growing concerns that if the tit-for-tat blockade escalates into a prolonged standoff, the global economy could suffer significant consequences.
U.S. Central Command: "All Maritime Traffic to Iranian Ports Blocked"
The United States Central Command (CENTCOM), which oversees the Middle East, issued a statement on April 12, announcing, "In accordance with President Donald Trump's proclamation, we will begin a blockade on all maritime traffic entering or leaving Iranian ports starting at 10 a.m. Eastern Time on the 13th (11 p.m. Korea Time on the 13th)." The statement continued, "This blockade will be enforced equally on all vessels of any nation entering or leaving all Iranian ports and coastlines facing the Persian Gulf and the Gulf of Oman. Ships that do not have Iranian ports as their point of origin or destination will not have their freedom of navigation impeded."
On the same day, President Trump warned via his social media platform Truth Social, "We will begin the process of blocking all vessels transiting the Strait of Hormuz." This is seen as a retaliatory action following the breakdown of ceasefire negotiations.
Mohammad Bagher Ghalibaf, speaker of the Iranian parliament and leader of Iran’s negotiating team, stated on the social media platform X (formerly Twitter), "American consumers will soon long for $4 to $5 gasoline," emphasizing, "We have not succumbed to total war, economic sanctions, or political pressure. In fact, we have shown the world just how desperate our enemies really are."
Tit-for-tat Blockade After Negotiation Breakdown... U.S. Aims to Cut Off Iran’s Funding
The U.S. decision to enforce a counter-blockade on all Iranian ports is analyzed as a move to entirely sever Iran’s war funding. According to CNN, since hostilities with the U.S. began on March 28, Iran has blocked the Strait of Hormuz and collected passage fees of $2 million (approximately 3 billion won) from some ships. In addition, Iran has exported an average of 1.85 million barrels of crude oil per day through major ports during the war, using the proceeds to fund its war efforts.
If the United States successfully imposes the maritime blockade, Iran’s economy is likely to collapse. CNN reported, "Since the outbreak of the conflict, most Iranian vessels have been sunk by U.S. military attacks, making it difficult for Iran to resist the U.S. Navy’s maritime blockade." The U.S. Navy announced that it had sunk over 150 Iranian vessels by early this month, which is estimated to be about 90% of Iran's prewar fleet.
However, Iran’s avenues for retaliation are not completely blocked. Iran’s major ports are located on narrow straits close to the coastline, making them vulnerable to attacks by drones and small suicide speedboats. Farzin Nadimi, a senior fellow and Iran expert at the Washington Institute, told the Wall Street Journal (WSJ), "The Islamic Revolutionary Guard Corps (IRGC) still retains more than 60% of its highly mobile speedboats in operational condition," adding, "Operations in these areas remain vulnerable to drones, speedboats, and naval mines, even though the Iranian Navy has been wiped out."
International Oil Prices Rise Back Above $100... Concerns Over Prolonged Blockade
Following the U.S. announcement of the counter-blockade, international oil prices soared again, climbing above the $100-per-barrel mark. As of 7:40 p.m. Eastern Time on April 12 (9:40 a.m. Korea Time on April 13), West Texas Intermediate (WTI) crude for May delivery was trading at $104.21 per barrel, up 8.33% from the previous session, while Brent crude was up 8% at $102.82 per barrel. This is the first time in four trading days that international oil prices have risen above $100 a barrel.
If the tit-for-tat blockade continues for an extended period, it is expected to further destabilize oil supply and demand, placing a heavy burden on the global economy. Rory Johnston, founder of Commodity Context and an oil market analyst, explained, "The war between the U.S. and Iran has so far reduced global oil supply by 13 million barrels, or about 12% of the world market. If the U.S. completely blocks Iranian oil exports, another 2 million barrels could be lost," adding, "This will mean additional costs for the global economy, which is already suffering from the blockade of the Strait of Hormuz."
Meanwhile, some have raised concerns that the U.S.’s unilateral maritime blockade of all Iranian territory could be a violation of international law. Citing U.S. legal experts, the BBC reported, "Such a unilateral coastal blockade could be considered a violation of international maritime law," and questioned whether imposing a military blockade during a ceasefire might also breach the terms of the ongoing ceasefire negotiations.
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